The "twice proficiency" option is lacking some of the options in the "proficiency" section. For example, you can't select "Choose an artisan's tool" from twice proficiency.

Are you referring to the ‘Prodigy’ feat, the ‘Expertise’ function of the Bard and Rogue, or Dwarven stonecunning?

I'm trying to create a homebrew race. It seems like all the same options should be available in both proficiency and twice proficiency.

Use Expertise modifier instead.

The Twice Proficiency modifier is a behind the scenes mechanic to affect proficiency bonuses in more ways and essentially adds additional bonus equal to proficiency that stacks with Expertise. The point of this modifier is to add additional proficiency bonus even if the character already has Expertise. It is very rarely used. It is typically for use in spells and feats to avoid conflict with Expertise.

From a subclass/race feature perspective there is no reason for you to be using Twice Proficiency over Expertise. This is why it is limited.

Ah ha! That makes perfect sense. Thanks so much, I'll switch those to expertise!