As best as I can recall, on every flight I've ever been on, when the safety announcements are made in two languages they are done sequentially. First the whole thing in Norwegian (say) with the accompanying demonstrations; nearest exits, floor lighting, decompression air masks, lifevest strap, lifevest inflation, lifevest whistle, lifevest light, etc. And then the whole thing again in English with the same demonstrations again.
On my little KLM flight from Linköping to Copenhagen it was different. This time the two languages were interleaved. The steward demonstrated the nearest exits whilst the canned audio spoke the appropriate nearest exit words in Dutch, but then rather than moving on to demonstrating the floor lighting (with appropriate floor lighting canned audio in Dutch) he immediately demonstrated the nearest exits again whilst the canned audio spoke the appropriate nearest exits words in English. Nearest exits taken care of, the steward and canned audio moved on to the next topic, floor lighting - again first in Dutch with a demonstration, then in English with the demonstration again. The effect was that even though I don't know Dutch I saw each demonstration twice.