Why hex address addition are not the same in gdb and python

This addition is getting me crazy:

In gdb : p 0xf7e280e0 + 0xefdc8000 = 0xe7bf00e0

In my python(3) script : 0xf7e280e0 + 0xefdc8000 = 0x1e7bf00e0

Why the result is not the same ?