To dual boot Mojave and Sonoma is a fairly easy fix. You don't need another EFI, you simply need to edit your current Sonoma booting config.plist, so the older APFS drivers used in Mojave & Catalina are allowed to be used.
- You need to open your config.plist in your preferred Plist Editor, I use ProperTree.
- Navigate to the UEFI section.
- Then within the APFS sub-section, you need to edit the MinDate and MinVersion entries to allow Mojave to boot.
This table from the Dortania OpenCore guide shows the MinDate and MinVersion entries required for High Sierra, Mojave and Catalina.
View attachment 576034
OpenCore defaults to Big Sur or newer, so only these three older versions of macOS require edits to the config.plist.
The screenshot below shows the current settings for the UEFI > APFS section in your config.plist.
View attachment 576037
This is how it would look after adding the MinDate & MinVersion entries for Mojave.
View attachment 576038
With this change you can delete the Clover EFI from your 1TB drive, and just use OpenCore to boot in to Mojave and Sonoma. Both OS's should show an icon on the OC desktop, without any further input on your part.
The EFI attached below has a config.plist that has been edited as shown above.
Try it on a spare USB pen drive and see if it allows you to boot Mojave from your other drive.