I've had a 2L stater overflow a 1 gallon jug before. it continued to do so for over 12 hours. Ended up tossing it because I didn't think 1056 was the only thing in there.
Wyeast 1332 harvested from a (1st generation) starter April 4th
Just the yeast & 1800 ml of wort (1040) that I canned from a previous brew day.
Stepped this yeast up as well for my 1st 10 gal batch.
I find them completely unpredictable. Same yeast, same size starter, similar temps, different results. Some are mellow, and some explode. After cleaning one up twice -- once in the middle of the night -- I'm resorting to fermcap.
You can't do a 2L starter in a 2L flask. I have a 2L flask and generally do 4 cups (750ML) starter wort. One or 2 crawled out of the flask. Those dawgies need range to run free!!! Would you do a 5 gallon ferment in a 5 gallon bucket?
That's nothing... Belgian wit 410 blew a WAY bigger load than that when I made a 1500ml starter in my 2l flask with no foam control. I bought a 5l the next day.