That's what we were trying to figure out yesterday too. Hopefully a member running tests will be able to report back what he learned so far.

A person mining with 18.5 MH today received 0.14614399 at a rate of 0.00789 BTC/MH/s paid

Another person with a rate of 11 MH received 0.064 at a rate of 0.00582 BTC/MH/s

This is a substantial difference for two miners who mined the same time period with very consistent hashrates.

The thinking right now is the higher-paid miner is the newer one, and is probably on a "Beta" server, while the older lower-paid miner is on the "main" middlecoin server. This would in turn mean the servers are not mining the same coin, or are being exchanged in different ways or at different times.

The hashrates were both consistent throughout the day, and I'm looking at accepted... not accepted + rejected

If anyone has any other ideas (other than they are on different pools / the conspiracy that older miners are getting funds siphoned off the top) I'd love to hear it