Don't keep two similar solution working at the same time. Keep the one that has the better foundation, implement the most important feature of the second platfo

Don't keep two similar solution working at the same time. Keep the one that has the better foundation, implement the most important feature of the second platform and migrate over all customers, kill the other one. If you don't do that, you will have to do it in a few years and you will have lost all those years. Start with the vision of the company, which one is better suited to go to that vision ? Ignore all the details. I know it is hard, but that's a complex situation and it needs strong decision and leadership