Can you Send Coins back from a Receive Address? We are setting up some merchant functions 

If a customer sends too many coins in a transfer for an order 

Can you send the change back to address you received the coins from .

i.e
1) Order 1234 12.5 BTC Merchant Recieve Address (1234abc) 

2) Customer Sends 12.6 BTC to Merchant Address (1234abc) from his Address (4567def)

3) Merchant detects overpayment And sends the 0.1 btc back to customers (4567def) Address as change 

Will this work in that the customer will get his change ??
This is not recommended.

If the customer uses a fully controlled wallet he will get the coins, but will be confused about their source because the address would carry the label of some other provider.

If the customer is using a shared eWallet, he might not get the coins at all because the address isn't his.