Let’s put this into context, photography was not invented, but discovered by various people at different periods in history using a multitude of different processes. The overlap and variations are too numerous to mention. Take any of the halogen compounds and experiment with them long enough and you get an image. There are still many variations of basic chemical imagery yet undiscovered and untouched and well worth a lifetime of experimentation. However, Daguerre was unique in his particular process of image permanence, be it only a one shot process.