Re-loan should not cause automatic renewal of items already on loan
When loaning an item to a patron, who has this item already on loan, the system automatically renews the loan (if possible). An option in configuration is needed to suppress this automatic renewal for the following reason: too many errors occur, when the item is automatically renewed. If the patron intends to return the item and the circulation desk operator by accident scans the item for loan, then the item is back in the library stacks but by accident renewed for the patron (who will get claimed!).

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KF commented
If you are having a problem with circ desk staff scanning returns into the check-out box (we do!) please consider supporting this idea: https://ideas.exlibrisgroup.com/forums/308173-alma/suggestions/32210845-differentiate-returns-screen-from-patron-look-up-s
Thanks!