After installing Product Update 1 for Sage 100 ERP v4.50 (Formerly Sage ERP MAS 90 and 200) you may notice that your form codes are suddenly duplicating when you perform a lookup.

This appears to be a known issue and Sage have a knowledgebase entry :

 

Multiple form codes appear in Form Code lookup in 4.50 after installing Product Update 1

 According to the entry a fix is pending and hoped for a release prior to or within the next product update.