Yep, that's better. The security on macOS is different and tries to protect you from accidentally overwriting what you may not want to replace. What I would do to accomplish what you want is to open "test" on the target drive (where everything will end up) and then in a new Finder window open test in the source drive (in your example, the one with files 1, 3 and 4). Now select all in the source drive by either clicking on the top once, then move to the bottom, hold Shift and click so that all are highlighted, or by using CMC-a to select all. Now you have several option to copy these files--you can drag them from one window to the other, or you can use CMD-C to copy them and then click in the target window and CMD-V to paste them, or you can use the Finder menu on the top bar to select Edit and "Copy" in the source window and then move to the target and select Edit and Paste.
In either case when there is an existing file with the same name, as Bob indicated, the system will ask if you want to replace what is already in the target area or keep both or cancel the copy. Pick what you want. If you say "keep both" then the moved file will have a number appended to differentiate the names, so in your example the moved 1.txt file will become "1 2.txt" where the "2" indicates it is the second file of that same name.
One more way to make what you want, if the file list is short, is not to select 1.txt from the source if you don't want to overwrite 1.txt on the target. But if the list is long, I understand the difficulty, so you can just let the system alert you each time.
EDIT: One challenge is that the options you are offered don't include a "Continue" but just to Keep Both, Overwrite or Stop. But if you always want the source to overwrite the destination, you just select that and it happens. So basically, if you want to keep the older, then keep both, then sort by filename and the two will be next to each other and you can delete the one you don't want.
