There's nothing shocking to anyone who knows how music recording (in particular stoner / doom metal) happens. Recording yourself several times is standard practice (it's called doubling or quading in sound engineering terms). It fattens the sound because the performer will not play exactly the same thing twice: it is just like having two guitar players in unison. Recording with several microphones is also standard practice. Mic placement has a HUGE influence on the sound you get so you will usually use at least 3 mics when recording a guitar amp; more mics just gives you more flexibility to achieve the final mix.
