In recent RouterOS versions entries with dynamic flag and comment "added by vlan on bridge" get automatically created in bridge-VLANs when a VLAN interface is created on a bridge. The VLAN interface is then listed as current tagged in this entry.
Despite this automatism it is still possible that a new or existing manual entry exists with the same VLAN ID and the same VLAN interface listed as current tagged.

Wouldn't it be wise to avoid these duplicates in a future RouterOS version and display tagged and untagged ports in the same entry?

The background is the comments you see explain the "why" it was dynamically added. Since they were added for different reasons, there are multiple dynamic entries.

In this scheme, you can already have a static and dynamic (so a "duplicate") for same VLAN in /interface/bridge/vlans. So I'm not sure it's terrible there are multiple dynamic VLANs shows.

The whole topic of the bridged vlans starts confusing... So whether multiple dynamic entires with comments is "easier" than just one dynamic entire lumping everything together is a pick-your-poison sitution.

If wrote script/tool that "visualizes" the bridge configuration here:
viewtopic.php?t=214189#p1123276

Since the presentation is tough to read even with just one dynamic and one static configured....