We add in the special prayer עננו on fast days. It is added in two different locations. (1) as a separate brocho between גואל and רופא and (2) as an addition into the brocho of שמע קולנו.
In (1) the closing phrase which begins כי אתה is needed before the closing brocho.
In (2) it seems to me that that closing phrase is in a sense duplicated by the closing phrase of שמע קולנו which also begins כי אתה.
Are there any nuschaos which drop one of the closing phrases when עננו is said in שמע קולנו?