Assign a unique random alphanumeric value to a column of random alphanumeric values

Hello, First timer here.

I searched for an answer and came up with different parts of a solution but i just can't string it together.
There is a column of data with random alphanumeric values (that may repeat) which need to be transformed into a different set of unique values in a different column:

b4527dcb636f

b8b42e7703cd

b4527de48f23

b4527dcb636f

So far I found the functions RANDBETWEEN + CHAR(RANDBETWEEN(65,90)) + CONCATENATE() which can help me create a new value. The new value parameters are irrelevant but i would like it to have 3 letters and at least 3 numbers.
Still, what i can't figure out is how to assign the same value (in column B) to a repeating one (A).

Sorry for the crappy English, it's not my native tongue.
Any help is appreciated!

Your english is fine but Im not understanding your request, what exactly do you mean by "assign the same value (in column B) to a repeating one (A)." if you can provide some examples that would be appreciated.

The values in the database may repeat themselves so:

A	B
b4527dcb636f	abc123
b8b42e7703cd	odb487
b4527dcb636f	abc123

The formula must give the same value to an already adressed unique value.

Am i explaining myself ?

thank you