Hi,
Well, the reasons I would do it would be...
You will still have a chance at offspring if one male isn't intrested or is shooting blanks.
It can increase the chances of you getting any specific requirements. Say you had 5 normal females and a pastel male and a spider male. But you desperately needed to produce female spiders and female pastels.
Breeding both males to all 5 females means you have 5 chances of getting eggs that have the genes you need compared to breeding each male to only one female and that female deciding not to produce that year. The odds per egg remain the same but the number of possible eggs you are dealing with goes up fivefold on average.
It means you genuinely don't know what you might get in each clutch - fun is also a reason.
It is quite important however not to do it with morphs that produce non-visual hets as there would be no way of knowing what genes were in what snake at that point.
As long as you stick to morphs where the heterozygous form is visual ( like pastels, spiders, black pastels, pinstripes etc ) then you should be able to pick out who fathered which egg except for the normals who wouldn't be carrying any of the fathers morph genes at that point anyway.
dr del