If I need to file a second amendment to my 2019 taxes how do I know if my first amendment has been processed?

[xmasbaby0]

STOP.  Do not even think about sending in a second amended return until the original return and your amended return have been fully processed--unless you want to cause confusion and delays that will take months to sort out.

You are already in for a long wait for an amended return to be processed.  Do not compound your problem by amending it again now.

   The IRS is not working on mailed returns now---and an amended return can only be filed by mailing it in.  Under normal circumstances you would be able to see something about your mailed in Form 1040X after about three weeks, but that is not the case right now.  The usual 4 months for processing an amended return is going to take longer.  Sorry.

https://www.cnn.com/2020/04/20/politics/irs-mail-trailers-covid/index.html

MAILED RETURNS

Per the IRS website IRS Operations During COVID-19: Mission-critical functions continue: The IRS is not currently able to process individual paper tax returns. If you already have filed via paper but it has not yet been processed, do not file a second tax return or write to the IRS to inquire about the status of your return or your economic impact payment. Paper returns will be processed  once processing centers are able to reopen. 

 If you mail a tax return (or a payment) to the IRS, it is a good idea to use a mailing service that will track it like UPS or certified mail so you will know it was received.

 TurboTax will not know anything about your amended return, and nor will TT know that you put your 1040X  in an envelope and took it to a mailbox.  TurboTax does not get updates on mailed  (or e-filed) returns.

When the IRS finally opens its mail and begins to process mailed returns you can check the status on the IRS site.

https://www.irs.gov/Filing/Individuals/Amended-Returns-(Form-1040-X)/Wheres-My-Amended-Return-1

https://www.irs.gov/filing/individuals/amended-returns-form-1040-x/amended-return-frequently-asked-q...

[rjs]

You will get a letter from the IRS when they have finished processing your first amended return. But as xmasbaby0 has described, it's going to be a long time before you hear from them.