The 50% het refers to each gecko having a 50% chance of either being het for albino or not. The only way to know if both geckos are het. is if an albino is produced, and you could produce several babies that are not albino before getting one albino. However, if both geckos proved their albino het. to be true, the odds of producing an albino are 25% or 3:1
However, in this case, it is generally not recommended to breed any kind of enigma with another enigma