well, that's nothing in this world existed to be directly comparable, once you are released in different time frame, different year, different competitors, during demographic, different level of WOM, there wont be a directly comparison.
We just need to ensure an as fair as comparison and including rerelease data into final nominal gross is certainly a fairer comparison. However, the number of times getting rereleased should also consider like GWTW and Snow white that getting multiplessssssssssssssssssssss rerelease is really against my argument.
But JP, star war 4,5,6,&1, titanic, well, that just re-released once or twice,so that shouldn't be a big problem in interpreting the movie performance, since we have neglected so many factor that work against them like the expansion of foreign market recently,inflation, and 3D-IMAX premium.