I don't think that any
eliquid vendor has any legal ownership over their recipes. It's possible that some of them may patent their recipes, but I can't fathom vendors doing this due to cost and, in a sense, 'useless-ness'. Lets say I make a recipe like this
10% TFA Peanut Butter
2% TFA Menthol
Now that you know exactly what my recipe is, you can steal it and avoid a lawsuit at the same time by mixing this
10% TFA Peanut Butter
2.1% TFA Menthol
Thus, the patent becomes rather useless. On top of that, it would be legally very difficult to take someone to court because 'their stuff tastes similar to our patented stuff'. You would need hard evidence that a competitor is indeed using the ExAcT same recipe, down to the tenths of a percentage and with the same flavor vendors (including nic, PG, and VG vendors).
With that said, I highly doubt getting it lab tested will tell you very much. All juices are pretty similar in composition imo. What you would get back would be pretty obvious stuff. Lets say "VegasVaap" is a chemical compound that makes bananas taste like bananas. You send in Gorilla
juice, for example, and it shows positive for "VegasVaap". Well, that doesn't help. Now you still need to figure out which flavor manufacturer he's getting his banana from and what % to mix it at, along with the same information for all the other ingredients, and the lab you sent it to couldn't possibly tell you any of that stuff.