Connecting phone chargers in parallel
The voltage drop in the diode will make the voltages in the two chargers unequal(as if they already weren't), and one charger will probably carry more current than the other, that one will hit its current limit and might shut down to protect itself. If you leave the diode out of course there might be a short. Paralleling these is generally a bad idea(series on the other hand is a less bad idea with isolated power supplies, but that doesn't help much here)

It might appear to work, but one charger will be pushed to 100% or more, there might be EMI/noise issues, and chargers are too cheap to bother with. And besides, old chargers are great for all kinds of things :)

You might be able to use resistors of just the right size to share current accurately, but why bother?