I have a new Canon Pro-10 Printer. I uninstlalled Elements 2018 and installed 2020. Then I found out that the printer does not have the plug in ready for 2020 yet. I need to reinstall 2018. It still shows up in my products with serial number, but I have not been able to figure out how to install it. I can't find it on the Adobe site. Can I have both on my computer at once?
Yes, it's fine to have both 2018 and 2020 installed on the same computer. To your 2018 installation question, if PSE 2018 isn't showing in your Order History it's because you bought it from a store or an e-tailer. In that case, you can't download the 2018 installer again but no problem reinstalling the original if you saved it somewhere.