WRT taping magazines together: Taping two together with one inverted has been done and can be seen in puppygod’s photos. Check the guy out in photo 9. He’s the guy with the beret pulled over his eyes. He has his magazines taped together in the “improved” way. They are all upright and have spacers between them. When he changes magazines, he releases the catch and just makes a small lateral movement to get to a full magazine.
Commercially-made clamps are available for sale that allow one to do the same thing. As for whether it is professional or not to do this, all I can tell you is that some companies, like Sig for example, sell magazines for their military rifles that are factory-designed to snap together with no clamps or tape needed.
The upside of using “jungle clipped” magazines is that you have a reload right there on the rifle that is quick to deploy. It’s especially popular among irregulars because they, as a group, are chronically short on things like load-bearing gear.
There are several downsides. It changes the balance of the rifle. It adds weight to the rifle. Because it changes the way the magazine “hangs” in the well, it has been known to cause malfunctions. It has been known to break magazine catches due to the extra weight.