With the dual class mechanics the way they are, dual classing too many characters is not a good idea, as you will end up with a party of effectively useless characters with high HP.

Has anyone ignored that rather obvious piece of advice (or not realized it would be a bad idea)?

If so, were you able to complete the game? How long did it take before you could reliably win battles in a reasonable amount of time? (I suspect that 20 THAC0 and 1st level spells (at caster level 1) would not be particularly effective against even the early enemies in the later games.)

This topic applies to the games that implement dual classing, including Curse of the Azure Bonds and its sequels, and could also be applied to Icewind Dale (which lets you create your whole party and implements dual classing).

Well, you could alway dual all your your newly created characters, with no loss of XP, and gain some small benefits like mages able to wear shields and armour, for istance.

Except that, of course, the start of the game is designed for characters who are higher than level 1, and dual classed characters start back at level 1. (Remember, Pool of Radiance didn't implement dual classing, and the Infinity Engine games don't let you dual class a level 1 character.)

Of note, a reasonable strategy is to duplicate a character and dual class the clone (or dual class both into different classes).

Yeah, forgot about that.
I'm just too used to playing FRUA these days, where dualing a lvl 1 character may be an option.

I thought you didn't like exploits? (Dual-classing at level 1 definitely feels like an exploit to me, since you get some of the benefits of dual-classing with none of the downsides.)

The way I roll my characters it may be the only way to get a Cleric with 18 WIS or a Mage with 18 INT.