To put it another way (and with illustrations), a standard domestic cassette deck has two MONO tracks on each side: With one track being for the left side of the stereo picture and the other for the right (the middle uses both equally).
Thus
1 -->-->-->-->-->
2 -->-->-->-->-->
2 <--<--<--<--<--
1 <--<--<--<--<--
Which is why you have to turn the cassette over to listen to/record on the other two tracks.
A four track, on the other hand, can play/record all four tracks at once (well, the better ones can).
Thus
1 -->-->-->-->-->
2 -->-->-->-->-->
3 -->-->-->-->-->
4 -->-->-->-->-->
But they're still four MONO tracks.
In order to achieve true stereo you need to utilize an odd and an even track TOGETHER when recording. Simply copying one track to another will not give you stereo. And putting it in the middle is just centre panned mono.
If you're desperate to have something in stereo (drums, say), the best way to go about it would be to record them on two tracks of the 424 (along with, say, bass and rhythm guitar on the two remaining tracks), then bounce all the tracks to a second recorder, and then bounce them back to two tracks of a fresh tape in the four track. You can then add another guitar and a vocal to the two empty tracks.
The best second deck would be either your PC, a standalone CD RW, a DAT player, a Minidisc player or a 2 track reel to reel. A normal cassette deck would be way down on the list.
