you can copy them back onto a special cartridge, but not onto an existing game, since the games themselves are stored- on actual ROM chips- (that is, nothing like today's "ROM" chips, where you could flash them... the data was physically ingrained in the circuits).
Also, from one of my old SNES manuals:
IMPORTANT
WARNING: Copying of any Nintendo game is illegal and is strictly prohibited by domestic and international copyright laws. "Back-up" or "archival" copies are not authorized and are not necessary to protect your software. Violators will be prosecuted.
This Nintendo game is not designed for use with any unauthorized copying device. Use of any such device will invalidate your Nintendo product warranty. Nintendo (and/or any Nintendo licensee or distributor) is not responsible for any damage or loss cuased by the use of any such device. If use of such device causes your game to stop operating, disconnect the device carefully to avoid damage and resume normal gameplay. If your game ceases to operate and you have no device attached to it, please contact your local authorized Nintendo retailer.
The contents of this notice do not interfere with your statutory rights.
So... yeah I don't think it's allowed
In fact that also applies to things like the Game Genie- using that voids the warranty on both the console and the game itself. That being said they generally don't damage the games, at least not that I've seen. And I doubt they'd be able to know anyway. Add to that that I have a strange feeling that games from 1992 aren't under warranty anymore, anyway, so your not really voiding anything to begin with.
Anyway, I believe the devices, nowadays (according to my lurking on the ZSNES forums) are called "game dumpers" or "ROM copiers". I've never heard of one with a floppy drive though, since the only ROM that was smaller then 1.44MB that I'm aware of was Super Mario World. (Chrono Trigger, for example, is over 4MB in ROM format). I wonder how it worked- it must have compressed the game, or not even dumped into the ubiquitous SFC format. (which has been bastardized into SMC... SFC="Super Famicom Cartridge"... SMC doesn't stand for anything, that I can tell.
The nice thing about the games with Battery back-up is that the batteries are the CR2032 that are so easily obtainable, and it's a simple process (with the proper screwdriver bit to open the cartridge) to replace the now often 15-18 year old batteries with nice fresh ones. In my case I got over 60% through the SNES zelda that I had just gotten of ebay- only to find, that it refused to keep any save games. But it was not because the battery was dead, but rather because- somehow or other - one of the contacts was bent and no longer on contact. removing the battery, bending it down, and replacing the battery fixed the issue.
perhaps the more exciting cartridges are those that use the SFX and SFX2 chips, since they use extra tabs on the left and right, and often posess some of the bulkiest circuitry that sometimes has trouble fitting in the game pak. (this is also why, for example, the Yoshi's Island cartridge is heavier then, say, Mortal kombat, or most other games.
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