how to determine whether the source code is same between two kernels

Hi, Suppose I have two kernels, one is A.B.C build by people Tom. And the other is A.B.C build by Jerry. The source code have been deleted after kernel is build and installed. Now I want to know whether the source code of these two kernel is the same (even if they have the same name). All I have is binaries (e.g. vmlinux, config, *.ko, System.map). Is it possible? Thanks