When I had government paid moves the same people came for the packing days and it was a different crew that did the loading. You might want to ask them the first day if they will be packing the next day too, and if they are the loading help also. Then you would know for sure.
The problem with tipping the first day if you do get the same crew is that they will expect the tip each day and yes, to me $60 to the same person is a lot!
I only tipped the packers if they went above and beyond, just the slow, not too focused packing did not get a tip. I moved lots and some packers were excellent, some were useless, many brought in backpacks and stole what would fit in their packs. I'd say make a recommendation that their stuff stays in their cars. They work in teams and one team had it down well, distract me with one with questions while the other wiped out the clearly marked do not pack medicine on the bathroom counter, or silverware, jewelry, etc. They focused in stealing the stuff marked do not pack. And I did not say a thing to them, but asked my neighbor to call the police, burglary in progress, and had their packs searched and them cited, and a new crew came
So for me tips is only if they deserve one.
I say $20 for the 2 day packing job per person would be more reasonable.