Last season there was an insane amount of multi sired clutches on this site. One was even with three sires and none of the babies were normals! This year all of my girls are getting bred with my spider and pastel because I can't decide who should get who. The odds of getting a multi sired clutch is low, but my females are all being breed and I'll get pastels or spiders or both!
There is no health concern with breeding a female to multiple males. Just give her breaks, feed her if she'll eat, and follow normal breeding protocol.