Payment out of my bank has duplicated as a deposit as well and if I adjust to clear the deposit it deletes the expense. My bank register across a number of statements

A duplicate deposit occurs when you've selected a bank account as the category while creating or categorizing your expense, Jble0802.
 
Let's say when you created an expense, you selected bank 1 as the payment account and set bank 2 or the same bank as the category. This treats the transaction as a deposit or money-in entry to the second bank. See the screenshots below for your visual reference of the scenario:

To isolate this issue, kindly review the expense transaction and select the correct expense category instead of the bank account for recording the transaction. This will help prevent duplication in your account register.
 
This thread remains open for additional inquiries you have.