rpm spec - Command rpmbuild modifies the binary -


the rpmbuild tool used generate rpm file using command

rpmbuild -bb sample.spec 

the sha1sum of 1 of binary inside sample.spec computed before rpmbuild.

after sample.rpm build, extracted using command rpm2cpio sample.rpm | cpio -idvm

the binary in extracted directory has different sha1sum binary sha1sum computed earlier.

is expected? how avoid change made binary?