amend two returns at the same time?

[bbest2014]

I've found a mistake A in 2018 return, and the same mistake A and a mistake B (due to mistake A in 2018) in 2019 return. 

Now I want to file amendment for both 2018 and 2019, can I file both amendment at the same time, expecting IRS to look at them together, and to fix my 2019 return based on the amended 2018 return? Or do I need to file 2018 amendment, wait for IRS to get back to me, then file 2019 amendment?

Thank you very much!

[ee-ea]

You can mail them at same time but each in its own separate envelope.

[bbest2014]

Thank you!