Dalmatian spots are a trait, not really a morph, but some people do include it in the description - "patternless dalmatian". Usually to be called a dalmatian they need more than 20 spots, otherwise they are just a "dirty" gecko in some people's minds. It's a very heritable trait, some believe it is an incomplete dominant gene. So breeding two dalmatians is likely going to result in all dalmatian offspring, with a portion possible "super dalmatians" - which are geckos with a LOT of spots, or very large ones. Generally it's preferred to have a lot of spotting or none, but there are some that don't care.
Spots won't disappear, but more may appear over time. Sometimes a spotless baby at hatching may develop many as they grow.