It probably WAS the same show - it's unlikely their instruments were plugged in. I used to work with a musician and he told me a LOT of bands prerecord and lip sync.
Lip-syncing, prerecorded tracks, and backup musicians out of sight behind stage. There's a simple explanation for this. Fleetwood Mac and the Eagles discovered during their late 1990s reunion gigs that when fans are paying hundreds of dollars for a concert ticket, they want to hear the songs exactly as they remember them sounding on the radio. They don't care how it's done. This became the standard (as did showing up on stage sober and on time).