Channel is marked 2010 another is 2020

Hello there!

You have either our S380-21 or S385-21 channel balance, depending on the depth of the bottom fitting. You'll need to measure as shown in the image below to determine which Series is the best match. 

Comparison of the S378, S380 and S385 balance shoes.

I see that you have two different stamped balances, however. Are they from the same window? If they are, they should have the same stamps. With that said, I recommend you weigh the window sash to confirm the proper spring strength option. There's a chart you can refer to under the product description on the S380-21 and S385-21 product pages that will indicate what option is best based on the sash weight.