In need of a script

i am need of a script which renames files with below condition:

1. if file name starts with US, prefix a US before the name
2. if file name starts with AU, prefix a AU before the name

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Please post examples. You request doesn't appear to make sense - you seem to want just to double the first two letters of the filenames if they begin with US or AU.

US_some_name.ext --> USUS_some_name.ext
AU_another_name.ext --> AUAU_another_name.ext

????

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