I'm also a learner, but here's my take on your question:
If the number of adjective clause is 1, second pronoun is redundant; if the number of adjective clause is 2 or more, second pronoun is not redundant.
Example 1: who
1(a). He is a hero who men don't like and who women admire.
1(b). He is a hero who men don't like and women admire.
IMO, 1(a) and 1(b) are both correct. The different between the two is whether "men don't like" and "women admire" are written as two separate adjective clauses (a) or single adjective clause (b). If you wish to emphasize the difference in attitude towards "he" between "men" and "women", I would suggest going with 1(a), which would make "women admire" as a separate adjective clause and therefore emphasize it.
Example 2: where
2(a). The is a game where I play as a swordsman and where the mission is to kill the dragon.
2(b). The is a game where I play as a swordsman and the mission is to kill the dragon.
Same deal with Example 1 (both correct), with the difference between 2(a) and 2(b) being emphasizing "the mission is to kill the dragon" as much as "I play as a swordsman" (a) or not as much (b) by either making "the mission is to kill the dragon" a separate adjective clause (a) or not (b).
Example 3: when
3(a). Now is the time when we step up or when the government violates our rights.
3(b). Now is the time when we step up or the government violates our rights.
Example 4: that
4(a). This is a puzzle that I will need to finish by myself or that my brother will come and ruin.
4(b). This is a puzzle that I will need to finish by myself or my brother will come and ruin.
*Note: Examples 3&4 are slightly different from Examples 1&2 because it uses or instead of and; if they use and instead of or, the same rule as Examples 1&2 should apply.
If simplified, these example sentences can be read as:
(a). [Subject] is [object] [when/that (1)] or [when/that (2)].
(b). [Subject] is [object] [when/that (1) or (2)].
If (1) & (2) have direct consequential relationship (ei. "we step up" stops "the government violate our rights" from happening), both (a) and (b) can be correct; otherwise, both are incorrect with an exception.
The sentence form (a) can be correct if it has or implies either, as in
[Now] is [either] [the time] [when (we rise)] or [when (we fall)].
[He] is [either] [the man] [that (will save us)] or [that (will doom us)].
Finally, concerning omitting relative pronoun, ef.com instructs as thus:
The relative pronoun can only be omitted when it is the object of the clause. When the relative pronoun is the subject of the clause, it cannot be omitted.
Here's the link for that specific article: https://www.ef.com/wwen/english-resources/english-grammar/defining-relative-clauses/
