/usr/bin/codesign_allocate If the codesign_allocate environment variable is set, it identifies a substitute codesign_allocate tool used to allocate space for code signatures in Mach-O binaries. This is used by Xcode SDK distributions to provide architectural support for non-native platforms such as iPhones.
/usr/libexec/DeveloperTools/codesign_allocate codesign_allocate sets up a Mach-O file used by the dynamic linker so space for code signing data of the specified size for the specified architecture is embedded in the Mach-O file.