I don't think it matters having more than one day care centre, but you do have to be happy with the services your child is going to.

My DD goes to 2 different carers, just because the main carer doesn't (and has never had) the day I need available. She is perfectly happy at each place. We did have a failed attempt to put her in a childcare centre on that day (I thought it was a good back up plan for if our main carer is ever unwell, etc) BUT she hated it. I knew immediately, but persevered for 2 or 3 weeks and during that time she just got unhappier and unhappier - she was more fearful and clingy at home etc too.

To be honest, the accident/incident might've happened at your other kindy too, so unless it's part of a pattern of events I wouldn't worry about it too much. BUT you might like to spend a bit of extra time at the new CC, observe what they do and how happy your DS is there, and decide for yourself if you think it's an appropriate place for your son.