If you have only one copy of the code then you only have to fix the bug in one place, as opposed to a dozen. So there is significant cost savings. But there is a problem: when you make a bug fix you have to test all the different places it is used. If you don't then you could be breaking something while fixing something. If you have comprehensive automated tests then you can have just one copy of the code--if you introduce a bug while fixing a bug the automated tests will catch it.

If you don't have comprehensive test automation then you have to consider whether you can manually test all the places it is used. If the code is used in multiple products at your company--and you aren't even familiar with some of those products then you can't manually test all the places it is used. Under such circumstances it may be preferable for each team to have duplicate copies of some code. Not ideal, but practical.