The system searches on its own and finds multiple entries, merging into a single one.
To start the integration in the client list go to Options-Edit-Μerge of duplicate entries.
The same can be done in the inventory when I have many common products, going to Options again, editing and selecting Merging duplicate Entries will merge all the multiple records into one.
In addition, every step the program takes to unify a record, it shows me the duplicate entries and asks for my confirmation to merge.
