He did a GOOD THING!

If capacity is still a issue up the temp of the gas tank back to 150
degrees, then install a tempering valve

Set the valve to 125 or whatever you want. It limits the maximum
temperature going out to faucets to what its set at. So no one can get
scalded.

I nearly installed a tempering valve on my old tank, I was going to
take the dishwashewr water before the valve so dishwasher would get 150
degree water, and everything else 125....

About that time my tank failed so I went with a 60 gallon pro high BTU
tank. That fixed our capacity issues, but cost a fortune and only had a
6 year warranty

Sadly standby losses with 2 tanks will DOUBLE, If I were you I would
add lots of insulation to both!