That happens usually due to some prior season stress when the flower buds were forming. Usually too hot last summer. Thin those off unless there is nothing else.

This is most common in sweet cherry. Also happens in peaches. My Flavor Supreme pluot has about 50% doubles.

I get a fair amount of those Siamese twin fruits on 'August Pride' peach and 'Arctic Star' nectarine. Fortunately they present early and can be removed easily.

Thanks for the info. I have never noticed the twin fruits before. I have lots of other fruit trees just never noticed. Thanks