I recall somewhere from my guitar lessons that if bass is playing a root note, than guitar should not already repeat it on a lowest string. I'm putting some progression, where it ends somewhere unresolved on Amin7 to Bmin7 (full chords with roots on A and B on lowest E guitar string). Normally the bass would go also A to B, but actually C to D feels all right to me (C to D indicate major to dominant progression, but by doing Cmaj do D7 does not feel as good to my ears for this particular progression).
If your progression is Am7 to Bm7 and you want to avoid playing the roots you can just omit the roots on the 6th string for those chords. I believe that was the intent of the lesson you recall. You shouldn’t play C to D7, that is a completely different progression. The C chord with A in the bass might be ok depending on the voicing you choose but a D7 with its C note in the chord will create a bad clash with a B root on the B minor chord.
There are literally thousands of commercially released recordings that have guitars playing root position chords with a bass player present so there is no rule about this, it is simply an aesthetic choice. In jazz in particular it is a bit more common for guitarists to eliminate the roots from their voicings but sometimes they do choose to play them. Like I mentioned earlier, if you want to play rootless chords the chords themselves shouldn’t change, just the way they are voiced.
Am7 contains exactly the same notes as C6. Bm7 contains exactly the same notes as D6. Seems that there's a possibility the last two chords, rather than Am7 and Bm7, are C6 and D6. hence the bass feels more at home there.
However, that's not, I suppose, the question! There's no real 'bad practice' when playing bass and guitar and voicings. The bass, pretty well by definition, is going to be playing a root, or other, at least one octave lower than the same name note on guitar, so it's not a question of pitches clashing (lower notes that are close in pitch tend to sound muddy).
Only by actually playing what you think could sound good/bad will you know. Genre will also be a factor. Theory itself won't be of much help here. (As in so many places...)
Playing a different note "on the bottom" than what the bass is playing potentially adds interest to the part (especially if it is a passing note on the way to somewhere else) but it will be heard as an error if it is dissonant.
But playing the same note on the bottom as the bass player is not always a good idea because you are stepping on the bassist's toes and muddying his tone. Better practice is to omit that lower note from your chord so the bass part comes through more cleanly.
(FYI I am a bass player, in case you couldn't figure that out)
It's not a matter of bad or good practice. It's a matter of being aware if something sounds good or not.
Or let's say, it's a matter of figuring out what will sound best in a given situation.
Having the same root note as the bass may very well what sounds best in that moment, and if it is, go for it.
To find out, try different inversions (different positions) of your guitar chords, and listen carefully to how they blend with the bass, and choose what sounds the best to you.
For example, you'll find that in genres like Jazz, guitar and piano will often avoid playing the same low notes as the bass, while in let's say hard rock or metal, with lot of distortion involved, playing exactly the same notes as the bass will get you the result you want.