Counting Uniques using 2 Criteria

I'm looking to assign unique numbers to a list with duplicate IDs using one additional criterion ("bin" size).

As the sheet stands, I'm using a formula that numbers each new ID as it moves down the list (uniques!). I am attempting to identify when the same ID (would be duplicate) has a different bin size (as it's not actually a duplicate!).

You will find the desired results manually entered in row D. Any help or direction would be greatly appreciated!

Help.xlsx

Thank you!

Try this in C3 and copy down:

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Functional. Thanks!