What is the ending bytes in the MOV instruction in 32 bit applications in windows? (B8 mov)

Question

So i just compared NTterminateProcess between 32 and 64 bit version of a program, and the mov instruction which moves the syscall into eax is almost the same, both 5 byte, (both the B8 mov) but the only difference is that the last 2 byte in the 32 bit version is some random number which is not even used as the syscall number, for example opcode is its B8 - 2C000700, but the 64 bit is B8 - 2C000000, and that last part is not even used in the syscall number, the number in both of them is 2C, so whats the deal with that last 2-3 byte?

EDIT : yes it is in fact Wow64 process

EDIT 2 : heres the picture, as you can see some of them have something in the last 2 byte which is not part of syscall number, and for some reason only the ones that have their Zw shown have them, why!? also the rest of them are Zw functions as well, for example the black one is ZwQuerySystemInformation, but i dont get why its name is not showing! ( does it have anything to do with the last bytes of mov not having a number?)

(Picture taken in x32dbg)

EDIT3:

77C61FF0 | B8 36000000              | mov eax,36                                                                                     | 36:'6'
77C61FF5 | BA 508CC777              | mov edx,ntdll.77C78C50                                                                         |
77C61FFA | FFD2                     | call edx                                                                                       |
77C61FFC | C2 1000                  | ret 10                                                                                         |
77C61FFF | 90                       | nop                                                                                            |
77C62000 | B8 37000000              | mov eax,37                                                                                     | 37:'7'
77C62005 | BA 508CC777              | mov edx,ntdll.77C78C50                                                                         |
77C6200A | FFD2                     | call edx                                                                                       |
77C6200C | C2 0C00                  | ret C                                                                                          |
77C6200F | 90                       | nop                                                                                            |
77C62010 | B8 38000000              | mov eax,38                                                                                     | 38:'8'
77C62015 | BA 508CC777              | mov edx,ntdll.77C78C50                                                                         |
77C6201A | FFD2                     | call edx                                                                                       |
77C6201C | C2 1400                  | ret 14                                                                                         |
77C6201F | 90                       | nop                                                                                            |
77C62020 | B8 39001B00              | mov eax,1B0039                                                                                 |
77C62025 | BA 508CC777              | mov edx,ntdll.77C78C50                                                                         |
77C6202A | FFD2                     | call edx                                                                                       |
77C6202C | C2 2800                  | ret 28                                                                                         |
77C6202F | 90                       | nop                                                                                            |
77C62030 | B8 3A000000              | mov eax,3A                                                                                     | 3A:':'
77C62035 | BA 508CC777              | mov edx,ntdll.77C78C50                                                                         |
77C6203A | FFD2                     | call edx                                                                                       |
77C6203C | C2 1400                  | ret 14                                                                                         |
77C6203F | 90                       | nop                                                                                            |
77C62040 | B8 3B000000              | mov eax,3B                                                                                     | 3B:';'
77C62045 | BA 508CC777              | mov edx,ntdll.77C78C50                                                                         |
77C6204A | FFD2                     | call edx                                                                                       |
77C6204C | C2 0C00                  | ret C                                                                                          |
77C6204F | 90                       | nop                                                                                            |
77C62050 | B8 3C000000              | mov eax,3C                                                                                     | 3C:'<'
77C62055 | BA 508CC777              | mov edx,ntdll.77C78C50                                                                         |
77C6205A | FFD2                     | call edx                                                                                       |
77C6205C | C2 1C00                  | ret 1C                                                                                         |
77C6205F | 90                       | nop                                                                                            |
77C62060 | B8 3D000000              | mov eax,3D                                                                                     | 3D:'='
77C62065 | BA 508CC777              | mov edx,ntdll.77C78C50                                                                         |
77C6206A | FFD2                     | call edx                                                                                       |
77C6206C | C2 0800                  | ret 8                                                                                          |
77C6206F | 90                       | nop                                                                                            |
77C62070 | B8 3E000300              | mov eax,3003E                                                                                  |
77C62075 | BA 508CC777              | mov edx,ntdll.77C78C50                                                                         |
77C6207A | FFD2                     | call edx                                                                                       |
77C6207C | C2 0400                  | ret 4                                                                                          |

Answer 1

It seems you're looking at a Wow64 syscall stubs in 32-bit ntdll.dll. WOW64 can use a special value in the high part of the syscall number for so-called Turbo thunks. From WoW64 internals by "wbenny":

typedef struct _WOW64_SYSTEM_SERVICE
{
    ULONG SystemCallNumber  : 12;
    ULONG ServiceTableIndex :  4;
    ULONG TurboThunkNumber  :  5; // Can hold values 0 - 31
    ULONG AlwaysZero        : 11;
} WOW64_SYSTEM_SERVICE, *PWOW64_SYSTEM_SERVICE;

It seems this is done to speed up extraction of syscall arguments from the x86 stack area. The thunk number used in NtTerminateProcess wrapper (7) corresponds to Thunk2ArgSpNSp which has the following code:

.text:000000006B101C40                 movsxd  r10, dword ptr [r11]
.text:000000006B101C43                 mov     edx, [r11+4]
.text:000000006B101C47                 jmp     short Thunk0Arg

So the first dword from the x86 stack (to which r11 points) is sign-extended into r10 while the second is copied into rdx (equivalent to zero-extending into rdx).