Hello, i'm having an issue with copying rows from a table and modifying and reinserting them into the same table.

The problem is with the ID field, the data comes from a system out of my hands, and the ID field looks like this: ST3300DPAAAEAR

Each one is unique, but i obviously can't auto-increment the field, so when copying i'm trying to add "testmarker" to each of the copied rows (see sql)

Code:
INSERT INTO products (
		id,
		ProductName,
		Tier1, Tier2, Tier3, Tier4, Tier5, Tier6, Tier7, Tier8, Tier9
		) SELECT
		id = concat(id, "testmarker"),
		ProductName,
		Tier1, Tier2, Tier3, Tier4, Tier5, Tier6, Tier7, Tier8, Tier9
		FROM products WHERE Tier1="Freesports"
But i get this error: #1062 - Duplicate entry '0' for key 'PRIMARY'

Which i assume means, trying to concatinate "testmarker" onto the ID, isn't working. Anyone have any suggestions what might be going wrong? (is this the total wrong way to do this?)

Thank you!