Anyone tried a co-phased dipole?

This post has nothing to do with co-phasing, but because I tried a dipole I'll post it here...

After I was done with my new install, and playing around with SWR on the new truck. I figured I'd take a min and just play with the dipole idea again. I didn't expect to see much change, but what could it hurt adding more ground directly beneath was my thought?

So I stuck another 4' whip under the antenna stud using a pair of vice grips. And it moved my SWR meter from 1.5 to 1.6 across all 40ch. It surprised me that it hurt the SWR ratio... but I'd be curious to have an antenna analyser to see what it actually did to capacitance or resonance, and all the other stuff you egg heads talk about. J/K

It was just a fun try, but unfortunately it was a quiet weekend and no way to tell how far either was getting out.