Duplicate Receipt Changes Case

We are having an issue with receipts entry (P03B102).  Up until recently, entries in a batch with the same Receipt Number (CKNU), would get a yellow warning but still process with no issues.  Now, when there is a duplicate receipt number, we still get the yellow warning, but it changes the case of the letters from upper case to lower case.  To be more specific, for certain transactions, we use a receipt number of “NOCASH”.  Now when we enter an item into a batch, the first line with the receipt number of NOCASH goes in fine, but for any other