Is it safe to buy two straight-run ducks?

[Roosterboy]

I wanted to get some Indian Runners. I could always order some hatchery sexed chicks or i could buy two straight run show/breeder quality birds. I figure i win any way

male+male= Quite
female+female= Lots o eggs
male+female= Babies! But would one male and one female create problems?

 

[Wifezilla]

If it turns out you have 1 boy and 1 girl, you will have to get at least 1 more girl (oh darn!)