What steps will reproduce the problem?
I spent a great length trying to reproduce the issue and could never figure out the exact steps. I will explain what happens however.
I use Spamalyzer to monitor chat traffic for my addon. I noticed that LGT would occasionally have a very high number of messages for one or two players in the raid. They would come in from the affected player every 5 seconds on the mark (I noticed there's a throttle timer for 5 seconds in the code). At one point I modified the library to see what message was the cause, and it was the TALENT message as received from the other players.
I asked one person in my raid who was affected to reload her UI. I wanted to see if the 5 second spam would go away. And it did.
I debugged the code a bit but it's fairly complex and didn't see anything standing out.
I tried reproducing this with two accounts as a party converted to a raid and no matter the amount of zoning, changing specs, etc. that I did I couldn't seem to force the issue.
I've attached a screenshot as "evidence" to the problem.
What version of the product are you using?