If you are just entering the one Item # to get a second copy, instead of Adding a new Item #, try using Duplicate (from the Right-Click pop-up menu).
This should retain all the information for the Item # you are duplicating while allowing you to change other fields (condition, price, notes, etc.)
Unfortunately, this does NOT work if you select multiple Item #'s at one time.
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The CTRL + J was replaced by the F3 key. Pressing F3 allows you to just to an Issue in a Title (and that is all it does as you can jump to another Title).
One thing about it, however, is you have to type in the Item # EXACTLY.
If you are jumping to Item # 500, it if fine as long as there IS an Item # 500.
If there are only Item #s 500/A and 500/B, typing 500 will not take you there you would need to type in 500/A or 500/B.
Also, it IS case sensitive. Again in you have Item #s 500/A an 500/B, typing 500/a with not take you there.