While shopping for a new timing light on the Summit online catalog, I checked out the detail section of the product and there was mention of 'multi-spark compatibility'. Most of the timing lights that the search brought up indicated 'no'. Summit couldn't really explain what that really meant and suggested I contact the manufacturer. I called one of the more popular brands and was told that the processor they use in the light can't handle or keep up with the signal(s) of a multi-spark unit like MSD or my Mallory. So, please, educate me on what this means, if it's true, and how does everybody deal with this?
Side note; I think my tachometer may already be dealing with this. At 70 mph my tach shows 4,000 rpms with 3.55 gears--- most of the time! Occasionally it will display 3,000, which I think is more likely the case.

Make me smarter. Thanks