I'm not sure if this has been discussed before, but this came up as a question in the context of
UD_Ancient_Hebrew-PTNK and I couldn't find a previous issue: What is the recommended treatment of "inner objects", which are common in Semitic languages and variously referred to as "internal objects", "cognate objects" or in Arabic as "maf'uul mut.laq"?

The phenomenon is basically the systematic inclusion of a verbal noun as an extra object of its own cognate verb, in addition to a possible regular object (if the verb is transitive):

• Biblical Hebrew: יֹּ֥אמֶר הַנָּחָ֖שׁ אֶל־הָֽאִשה לֹֽא־מ֖וֹת תְּמֻתֽוּן׃ "the serpent said to the woman, you shall not die a death"
• Modern Hebrew: rutsu ritsa mehira "run a fast run!"
• MS Arabic: s.aama s.auman "he fasted a fast"

In modern Semitic usage for both Arabic and Hebrew, the most frequent contexts in which this is seen is either for emphasis, or when an adjective needs to be used adverbially, and the modified verbal noun serves this purpose (so "run a fast run" is like "run quickly"). In Arabic, if the verbal noun is dropped, you can still get an accusative adjective agreeing with the missing verbal noun and used with adverbial meaning (this is referred to as naa'ib maf'uul mut.laq).

How should this be analyzed in UD? In both Hebrew and Arabic, the accusative marking is explicit wherever the morphology allows it and looks indistinguishable from regular objects. When there is one object, I expect people are tagging this as obj, but when the verb is transitive ("bake something a thorough baking"), this would lead to a double obj analysis, which is usually avoided in UD.

Incidentally this phenomenon can occur marginally in European languages, especially in topicalized negation, which I think is possible in both German and Russian, at least with intransitives:

• Aber Schlafen habe ich nicht geschlafen "but sleep I did not sleep" (=I didn't sleep a sleep, i.e. I did not sleep at all)