MD lists forms of this verb s.v. two lemmas "ATR I" 43b and "TAR" 481a. The latter is incorrectly connected there to "ATR II" (i.e. (tr).
In Sam. TargA.var. to Lev. 20:23, should be translated as 'to be aware'.
See s.v. ˁrr for possible additional examples of the reduplicated form in JLAtg.
Note that this is one of the middle weak verbs whose non-D T stems we have separated into Gt and Ct depending on the semantics, i.e. on whether it is middle (Gt) or passive/reflexive (Ct).