Timing light question

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

I bought one of the cheap D cell powered timing Flaming River timing lights from Summit it works good on my race car with the MSD 7AL2 race box with the proper coil
Which MSD box are you using? If a race 7 type box are you using the tach feed on the end of the box? If not try that next

My old-school inductive light works fine with my MSD units.
Something in the dial-back lights is apparently a problem with multiple sparks.
I've always preferred the old timing lights anyway - don't think I've ever used a dial-back style.

My older craftsman inductive with power from the car's battery worked very good when there was not an MSD involved, but did not work very good on MSD. It had a tendency to jump around a lot. So I bought the MSD self-powered. It works very well with the MSD, steady as a rock. And the self-powered feature is very handy so I don't have to hook it to power when the battery is not under the hood.

I have a lightly used ferret timing light as well as an almost new Innova. I believe they are both compatible but not 100% sure. If at all interested PM me and I will verify.
BTW, The MSD 8992 light looks identical to the ferret

Most lights won't function correctly with a multi-spark ignition. The adjustable lights aren't accurate when trying to use to check total timing with the engine RPMs up.

Old non-adjustable Ferrets, old Sears/Craftsman/Penske inductive lights (2134, 2138), and any of those sold by MSD will. Adjustable lights should be avoided. Plenty of the old Sears lights on ebay, and occasionally, an older MSD chrome light or even a Ferret 81 show up. Or you can pop for a new MSD copy of the Ferret, MSD also does a battery powered unit. I think they are still made in the USA

Just for the fun of it I hooked up a cheap harbor freight dial back light to my Msd. When connected to car battery it wouldn't work. Hooked the feed to a spare battery I had and it worked perfect.

Both of my dial back craftsman light worked that way also