Suppose there's a Spark Double in play under my control that isn't copying anything and a Clone comes into play under my control.

Now I can choose to have clone can enter the battlefield as a copy of Spark Double. That means that there's another replacement effect which - it seems - means I can pick Spark Double again and so on. Eventually I'll have to copy something else or just not copy since it's a may ability.

Is that legal, and, if so, does it come into play with a +1/+1 (or loyalty) counter for each time it copied the Spark Double?