Each state rego authority will require a compliance cert from that state. It doesn't matter if they differ. If you want a Qld rego, you need a Qld cert.

Are you trying to sell ? IMO spend the money and get one for your state. Use it as a selling point and let any new owner sort out their own requirements.

Not selling, just trying to clarify gas compliance. SNSW advises original gas compliance plate is valid for the life of the vehicle unless modifications have been made, in which case it needs to be reinspected and recertified.
There is no requirement for recertifiying when transferring rego from another state into NSW. Rego inspections do not test or certify (habitation) gas installs, only check that the compliance plate is fitted.

Hi as a recently retired gas plumber Victoria ,I had to sign off on a gas compliance and keep paying my insurance for 6 yrs as thats my tenure of responsibility .However this plate remains ongoing unless regulations change . Cheers John .

Sorry P.S. If you own a campervan that requires a roadworthy certificate in Victoria you will need a new compliance certificate from a plumber .

In Western Australia, I had a caravan with a gas, (and electric) compliance stickers, for more than 10 years

I now have a motorhome with the same type of compliance stickers, for more than 5 years

No one has checked them, so I assume that they will last forever

In Qld vans etc require a new gas cert, no more than 14Days old, for registration transfer Other than that the gas cert lasts indefinitely

For WA, I have bought vans in the eastern States and registered them in WA. The original gas certificate is accepted unless there have been modifications which need further certification.

"In Qld vans etc require a new gas cert, no more than 14Days old, for registration transfer" Perhaps transfer is different to new registration, but a several years old certificate was accepted when we registered an unregistered motorhome recently