When you save the newly signed folder that has the same name and size as another one, the Mac operating system will always ask you if you'd like to replace the folder that already exists. It seems that you've picked the 'Replace' option, so the folder labeled with the same name as your new folder is overwritten. That is what we call an overwritten/replaced folder.
Don't worry! The overwritten folder will still store on your Mac's internal hard drive until new data is written in its place. But you can't find it from any location on your Mac using Spotlight because once it was replaced by a new one, the operating system will automatically remove it to free up space. You can consider your overwritten folder was deleted from your Mac drive temporarily and you still have a chance to get it back.
If you have backed up your Mac with Time Machine or iCloud before, you can recover the overwritten folder using Time Machine or iCloud. But if you have no backups in Time Machine or iCloud, then the data recovery software should be your last option to retrieve your lost overwritten folder.
iBoysoft Data Recovery for Mac is a professional data recovery software that can easily recover replaced files on Mac. This powerful data recovery tool is compatible with Intel Macs and Apple Silicon Macs with M1 and M2 chips and also works on macOS 13/12/11/10.15/10.14/10.13/10.12 and OS X 10.11, which is also able to recover emptied Mac Trash.
To recover the replaced files/folders from Mac using iBoysoft Data Recovery for Mac. You only need to download and launch it. Then use the Search for Lost Data function to start scanning all lost files on your Mac. Once the scanning process is finished, you can filter these recoverable files by different file formats so that you can quickly pick up the files you need.
Select the files you need, and click "Recover" to retrieve them from the Mac disk. Rember to not store the recovered files in their original place to avoid data loss.