It certainly is possible, but probably happens less frequently in garters than in pythons, based on the sperm plug. I am talking about the "real" sperm plug that garters produce to block other males sperm, not what the ball python guys incorrectly refer to as a "sperm plug", which is actually a hemipene shed mixed with a little "fluid", that they also incorrectly use to gage sexual maturity in males.
So with the sperm plug idea it is more likely the 1st male, the ery/flame mohr anery male that did the job, but anything is possible and these babies will have to be bred and proven for the albino gene from mother at minimum anyway, so could be surprise "lottery" babies next generation.