You can but there is no benefit for doing so ... the excess will simply be added back into your income  on the tax return so you will gain nothing.  

What if I spend over $10,000 a year in childcare? I don't plan to have any excess. 

You can spend a million dollars on child care ... but the limit on the day care credit  form 2441 is $5K per the IRS regs ... so although the employers may allow you both to put $5K in the FSA it will do you no good.  

Thank you, I think this is the answer I needed. But now I have another. If we file jointly does it matter which withholds the money since we don't make the same amount?

Thank you, I think this is the answer I needed. But now I have another. If we file jointly does it matter which withholds the money since we don't make the same amount?

<<If we file jointly does it matter which withholds the money since we don't make the same amount?>>

No, not as long as you file jointly and the total combined contribution does not exceed $5,000.

Thank you so much I appreciate your help so we can make educated decisions.