I've just replaced an old dimmer switch with a standard 1-way operating the bathroom lights. The first thing I noticed was two live wires in the common and one in the live. I simply wired the new switch the same way, which resulted in an unexpected outcome. The bathroom light switch now controls the kitchen light too! The kitchen light switch will only operate the kitchen light when the bathroom light is on. If the bathroom light is off then the kitchen light switch has no effect. The kitchen light has a single live going into the common and one going into the live. Any suggestions as to what is going on and how to fix it?