The 1000.2EA LNB is designed to mount on the 1000.2 dish not the dish 500. You can use a dish 500 with a DP or DPP Twin to aim at the 61.5 & 72.7 satellites, it would have a 10 degree spacing so maximum strength wouldn't be possible but you can get it to work.
The majority of the cost of a dish is the LNB, so instead of buying a mismatched LNB for your 500, just purchase a 1000.4 EA (preferably) or a 1000.2 EA.