Lyra2v2 is problematic for nvidia, the miner itself reports 30% higher hashrate than actual. Perhaps you should add a penalty for the algorithm on nvidia or check what miner gives a real hashrate.
If you use the DJM version of ccminer for Lyra2v2 you will get the correct hashrate reported at your machine and at the pool. I has a feature that has something to do with reporting (or not reporting - can't remember which) stale shares. I have used it for Miningpoolhub and on my own vertcoin P2Pool node and the hashrate matches locally and at the pool.