It's fun to say things like "you can never have too much....(fill in the blank...***, pizza, light...).
The truth is that too much light is very dangerous. If you're gonna spend alot of time at that workbench doing close-up work, then you can end up with eye strain, migrain headaches, and many other health issues.
To answer the OP's question properly, you'd need to know the height at which the lights are hung over the bench. Assuming a normal garage situation where those lights are 6 to 8' over the bench, 10,000 lumens is probably overkill and TWO of them would likely be pretty ridiculous. Most normal task lights are in the range of 4000 lumens.
Good luck,
CD