PAK44 Anti Tank can be researched without the previous upgrades

[Reaper]

Unlike PAK43, PAK44 only requires Industry III to be researched, so instead of going through a chain of upgrades (PAK40 — PAK43 — PAK44) you can jump straight to the best thing. This doesn't seem to be intentional.

[HauptmannHorst]

And if pak 44 is researched you cant produce pak 43 any more.

[Stratego (dev)]

@Jasondunkel how this should be?
a) parallel items producable (not upgrading each other)
b) they are upgrades of each other so only the latest invented version is producable.