Ambiguous name detected: Worksheet_Change

I have two different codes that I want to run on two different Worksheets and am getting the above error. Along with a solution to my problem, I'd really appreciate an explanation of why this happens so that I can understand the solution - I know that could prove time consuming, so will accept only if someone would help me get the code to work.

1st Code= Data is in Column 13 (M) to change input to Canadian Postal Code ?#? #?#

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2nd Code = Data is in Column 12 (L) and is for Canadian Provinces to ensure that it is only 2 Uppercase Letters (not exactly sure if it is correct)

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I do appreciate the hard work and effort it takes to learn this and am very grateful for any help given.

Thank you for responding so quickly.

I tried the code by going to the Worksheet right clicking on the tab and 'view code', then pasting the code.

I was in the Prov Column (12) and it only worked for that one cell I was in (L6) and no other ones in that column for the Province and of course the top code (postal code) didn't work at all. Not sure if I am not doing something right?

Here is the code I pasted:

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I have two different codes that I want to run on two different Worksheets

Sorry if there is confusion, I meant to say I am wanting to run the two different codes on one Worksheet

Thank you very much that worked so well!