Bubble or Apple... Same same but different

Zaccy is getting really good with words now, he will try to repeat most words that you say...  Which is sooo cute.  He however is still struggling with apple, for some reason it always comes out 'bubble'.  So we spent the morning trying to teach him apple.    Which he did get a couple of times, much to his own excitment (as he would then throw his hands in the air and go 'eayyyyyyy' his version of yayyyyy!!  However we now seem to be back to bubble for apple.  Which you would think would become confusing when he actually wants to play with the bubbles, but when he wants to play bubbles he then brings his hand up to his mouth and pantomines blowing.... SOooooooooooooooooooooooo cute...