Is to much yeast in wine a bad thing?!
Answers: I must agree with A mo you can't put to much yeast in. The first 24 hours yeast is busy budding and dividing until they reach an optimum population for the volume of must. Then they begin to ferment for alcohol. 2 packs in 5 gallons is plenty any more than that and you are wasting your money.
If you mean at the start of fermentation, it's never been a problem for me- I usually use 2x what's recommended. Too little can be a bit of a drag, though as it can take precious time to get going. If you mean once the wine's in the bottle, it could cause appearance and taste issues and even explosion if not completely fermented.