My personal humble opinion here fellows.... I do not like a ratchet strap at all. Too loud and cumbersome to me, but again JMHO.
As Fletcher said above... the straps that come on most hang on stands are the 2" wide non ratchet type that have the flat metal buckle you pull SNUG, not so D**N tight that you are at the breaking limit of the strap when you install the stand in the first place. Then the strap is further stressed from tree growth, wind storms, temperature swings,etc, etc. The longer the stand is on the tree the more these factors come into play. No wonder so many ratchet straps break each year !!!
If you are going to continue to use a ratchet strap then yes, please by all means use TWO, go with the wider ones and try not to ratchet them down to the breaking point fellows ! Remember, when you add your weight to the stand you are pulling tension straight down which acts to tighten the strap too.....