Sperm parameters can vary quite a bit from test to test for a couple of reasons. 1. Abstinance period plays a big role. if you abstain 2 days for 1 test and 5 for the next, things might be pretty differnt. 2. small things in life — like heat — can cause pretty big swings in sperm. So a 1 time exposure to something can knock you down for a few days. 3. semen analysis vary quite a bit due to the level of care and skill of the technician performing them. In an absolute best case, you are looking at a 10-20% difference if the same sample was divided and run by 2 different people. So a count of 10 million could really be 8-12. When you add natural varience to varience in testing you can get some pretty big swings.