As suggested If you have 2 nuts and get some spare copper olives for the ISO valves, then just fit these into the ISO's
When an experienced plumber fits new couplers/valves but uses the old nut and olive (saves cutting the plastic) then its prudent to use a wrap or 2 around the old olives, just ensures there's no leaksif you look at this photo then it looks like the pipe has PTFE tape under the valve. Why?