Error Message CJ606 Entry "SM" already exists

Dear Team,

I have been trying to create the Coding mask with SM (2 Char), in fact, in Golden client there is a coding mask already been defined with S (1 Char). I have seen various threads and unable to fix the issue.

The is a error message

Entry "SM" already exists

Error Message CJ606

Below threads didn't help me out. I have tried by enabling the first check box and changing the value of "PL" 2 as shown in the attachment.

https://answers.sap.com/questions/4562880/project-coding-mask.html

Could someone help me out to fix it.

Thank you in advance.

Regards,

Arunachalam. AN