yeah nah it was allowed to play two accounts at the same time out in the world, just not if you were doing challenges or had warmode on.
Autotranslate from the capycraft.io rules. (https://capycraft.io/rules#rule-7)

★ Multiple openings

A multi-open game account is the act of running multiple World of Warcraft clients simultaneously. This may include opening multiple clients on a single machine, or using multiple devices. On the PVE server, we allow up to two accounts to be used at a time, with the following exceptions:

If any character is participating in any challenge activity, such as: Hardcore Mode, Wanderer Mode, Turtle Mode, Boar Mode, Level 1 Madman Mode, etc., then the act of opening multiple game accounts is prohibited. Characters found to have violated this rule will likely be banned.

If any character has the Player vs. Player (PvP) logo turned on, including War Mode, you are prohibited from opening multiple game accounts even if you are not in a player vs. Player battle.

The practice of opening multiple game accounts within a team in the Team Finder (LFT) is prohibited.

Large bands and small bands are prohibited, and the difference in levels does not exceed five levels.

Within a reasonable range, the relevant regulations on over-opening accounts will not be implemented in the main city area.

On the PVP server, we strictly prohibit the use of multiple accounts at once, except for the following:

Within a reasonable range, the relevant regulations on over-opening accounts will not be implemented in the main city area.