To merge a customer in Y2 do the following
1. Back Office > Basic Data > Customers > Merge Customers
2. Select filter on duplicates (will use first name in this example)
3. Enter filter criteria (this examplewill use first name). Then select F9 to apply search
4. Select the fields to merge by clicking on them and pressing Space. They will go italic
5. Then select the tick to begin the process
6. Highlight the record you wish to keep and select next
7. Then select End to begin
8. Select yes to confirm
9. Once complete select quit
Customer Merge complete. Repeat for the next one.