The way they can hurt each other is by smashing into each other so if you can use some plastic bags to try to cushen them from each other if there large frags.
singly bagged my vote also. If something happens to one frag, say it takes shipping badly at least the others won't be affected. Only reason to bag them all together is to save on bags, time and weight. Basically just poor shipping being done.
When selling corals, even locally, I always put the frags in their individual bags to prevent damage during shipping. And if I was selling outside of my local area, I double bag each frag.
I purchased some online and got them all in the same bag. one frag fell off the tile, another frag was dead, a third frag had polyps falling off of it and the fourth looked ok but only about 2 of 10 opened. So I would vote No. Then I was told their death was because they didn't like my tank.