Do multiple encounters combine for craft?
I am assuming 4th edition (Fantasy Flight Games) here.

For the two cases you laid out:


If there are two Craft enemies on the same space, then according to the rules as written, their craft scores would be combined. The rules for Psychic Combat (combat using Craft) are literally Ctrl-C Ctrl-V the rules for Battles (combat using Strength), and then find-replace "Strength" with "Craft". So, yes, that rule does apply for encountering two enemies that attack with Craft.
If a Craft enemy and a Strength enemy are on the same space, both enemies are fought separately (one in Battle, one in Psychic Combat). The lower encounter number is fought first, then the other.