Speaker placement question

I know nothing about speakers, really, just records. That being said, I have two pairs of oversized speakers in my room and I've run outta space to put them. They are cheap, one pair's a Soundcraftsmen Lancer TX2640 and the others are KLH 4132s.

My question is whether there's any problem with putting one set on top of the other? Would this create a wall of sound, or is this not advised? Would it sound funny? Could one speaker's vibrations damage the other speaker on top or beneath it? Any other possible concerns?

Thanks for your help,
Running both pair at the same time will probably "muddy" the sound. It isn't a problem using one pair for stands? It won't damage anything. You really want the listing pair to be at ear height for the mids/tweeters. If you can't afford new speakers, placement can make a big difference on the sound. Spikes under the speakers will help with bass and tighten up the sound.