I believe this is more commonly known as "overlapping instructions/opcodes"; and it was a relatively common technique for size optimisation or obfuscation in the 80s and early 90s, when Asm was the norm for PC software.

To my knowledge, there are no tools which do a good job of presenting the parallel execution streams. Instead, the typical flow requires the human to iterate through attempting disassembly at different offsets.

I remember seeing one (tracing) disassembler which does this, presenting the different streams side-by-side until they realign again. No doubt cracking groups probably have their own private versions of such tools.