Help with identifying groups and sets

Hello,

I'm have a data set with a number of company names in column A (duplicates includes) and a number of trades in column B (duplicates included).

I want to eliminate from my list any companies that only employ 1 trade, but I figured first I would need to identify them. Can I get some help on how to identify which companies employ only 1 trade and keep all those that hire multiple?

The data looks something like the below

Column A
Company A
Company A
Company A
Company B
Company B
Company B
Company B
Company C
Company C
Company C
Company C
Company D

Column B
Ironworker
Ironworker
Carpenter
Millwright
Millwright
Millwright
Millwright
Millwright
Painter
Ironworker
Painter
Ironworker

Thanks so much

Brilliant, thank you