Are you sure it's not a typo?
The first two digits refer to the length of the longest edge, so you should be able to measure the holders to check that they are infact 9mm.
The only key digits are the DC_T090202. The 3rd letter is the insert tolerance, so isn't critical for normal use, with everything after the 6 size digits being manufacture specific to identify the insert material.
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This page has a breakdown of the codes - https://www.carbidedepot.com/formulas-insert-d.htm
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The main thing when purchasing tools, is the shank size. On a typical lathe ATC, you have to either ensure you use the correct shank height so the insert is at the correct height, or shim the tool to the correct height.