Romcenter

I loaded my datafile and then my romset, everything came up green : https://imgur.com/r963Jhh
Then I copied that datafile and loaded the exact same romset and everything came up red: https://imgur.com/2R4MVQ3
As you can see, the Crc/SHA-1 is no longer matching for the exact same game. What's going on?

I found that the problem was that the plugin was set to crc instead of nes.dll. I have found no way of changing the plugin in RC4 unless I go into the database file and type <romcenter plugin="nes.dll"/> in the header. Is there an easier way of changing the plugin? I get the one warning when I'm loading the database, and then I found it might change if I'm playing around with things, no way to change it back.

If no plugin is defined in dat, romcenter attempts to detect if one has been used to create the dat. The detection is based on crc of specific games for consoles (defined in romcenter.config file).
So, the best you can do is to put the plugin line in the dat.