AIBU to leave one party early to go to another

[Honeybeesintrees]

DS is 4 and was invited to a child from his preschools birthday party. This child will be in his reception class along with some of the others attending and we have RSVP'd to going. DS then came home with an invite from a child at his daycares birthday party happening the same day. In order to attend both we would need to leave the daycare child's birthday half an hour early and then go straight to the second party. AIBU to try and go to both parties or would I be better just going to the one we have already RSVP'd to?
DS has already said he would prefer to go to the party we have RSVP'D to but I suppose I feel bad for the other child

Ive been in this situation and done both. Total nightmare. Ds was over tired and just grouchy for the rest of the day and most of following day. Just way over stimulated. They were both in playcentres opposite ends of the town so rushing from one to the other. Left one early and arrived late to the other.
I'd go with the one that he will be in reception with. It's good for them to have a familiar face when they start so it won't be as scary.

I’d go to the second party late (obviously letting host no and checking that’s ok), otherwise he won’t want to leave the first party early and will
be grouchy. If he leaves at the end and arrives half an hour late to the second party he will slot right in.