There is a sensor inside the drive that detects when the disk is ejected and a new one inserted, and a signal is sent to the floppy disk controller to tell it that there is a new disk in the drive. However, if anything happens to cause this disk-change signal to not be sent properly when the disk is changed, odd problems and data corruption will result on your floppies, because the system will write incorrect information to what it thinks is a different disk than the one in the drive. If the drive was just installed recently, or you just worked inside the PC, you have probably either connected the disk incorrectly, or you have loosened or damaged the floppy cable. Double-check all connections and see if the problem clears up. Clean the drive .
Dirt can sometimes accumulate on the disk change sensor and cause it to stop working properly.
A head cleaner won't generally fix this problem, because it is not really related to the read head. You could have a defective floppy cable . Try replacing it. There could be a problem with the floppy disk controller. Try replacing the floppy drive and see if the problem clears up.