How to prevent going over 401k limit when ee transfer between companies

Last year we noticed one of employee went over 401K limit because he transferred from one company to another company.  What's the process in e1 when this happens?  For example, from co 1, we withheld $10,000 and employee transferred to co 2.  What we want to do is, withhold remaining balances to make up the 401k limit.  But what happen was, e1 withheld full 401k limit from the co 2 where ee transferred to.  Thanks!

Caroline