I stand corrected! I couldn’t find this symbol in any of my resources. I’m glad I asked a mathematician.
Equals followed by equals is a symbol with a specific meaning. To transcribe the symbol, follow Rule 24.1.f which says this: “The multipurpose indicator is used between two symbols of comparison to indicate that the corresponding signs of comparison are printed horizontally and not vertically.”
.K”.K
Then follow Rule 26.2 to select the runover site: start the runover line with the first equals sign.
The double equals sign is also found in programming, which is not the case here as far as I can tell.
Lindy