How do ROM managers work?
As you should now understand the concept of CRCs you should be able to see how a ROM manager can identify ROMs by their CRC then rename them to whatever a particular emulator requires. ROMBuild uses CRCs to identify the necessary source files then applies the appropriate conversion routines to them. ClrMamePro also supports MD5 and SHA1 but when enabled, processing is a lot slower than simply using CRCs.