Is it normal for some lights dim and other lights get brighter when appliances are turned on.

when testing voltage at outlets and panel I get a voltage drop to 100 volts on one line at main service and get equal voltage rise on the other line. 140 volts. Across the two lines remains consistent. 240 volts. This occurs when the 2 devices I'm using are on at the same time and on two different breakers but are on the same line of service panel. When swapping the 2 devices to different outlets on the other line of panel my voltage readings reverse. All other breakers of the panel are turned off during testing. The 2 devices draw approx. 13 amps combined.