They are not re-releasing lights, 6kg lights can filled by decanting from a Flogas 19 kg. @ around £35 for 19kg it makes a mockery of Calors £25 for 6kg, it's the same gas! To decant you need a straight through pipe with no regulators fitted, the supply bottle needs to be upended and fill the receiving bottle to the weight on the silver collar. I have Alugas lightweight bottles fitted in my motorhome now.
To refill Calor 6kg bottles from a 19kg Flogas bottle, at less than half the refill price of 3 X 6 kgs, you need a straight through pipe with fillings both end with no regulators. You have to upend the supply bottle and weigh the receiving bottle to the weight stamped on the silver collar, this gives the required air gap in the bottle. I am explaining how it's done. not that you should do it or that I have done it in the past.