like I said, not sure how two 401K plans work

If overcontribution happened in one 401K plan, I think the matching will be withdrawal too as the overcontribution is returned.  because the plan administrator would have a process for this. 

However since you have two 401K plans, each plan didn't exceed individual contribution, the plan administrtors won't know to trigger overcontribution return process. Even when IRS found out you have overcontribution from TWO plans, I am not sure how they would require withdrawal of excessive contribution, i.e which plan to return how much? how to notify the plans?  Maybe nobody would care and you just end up paying taxes and penalties and the money still stays in the plans.