ジョウ, チョウ, たた.む, たたみ, かさ.なる
tatami mat, counter for tatami mats, fold, shut up, do away with
JLPT2 G7 S12 F1665
畾 is a variant of an element adding another 夕 to the bottom left of 多 (tall, neat pile of meat). 疊 adds 宜 (originally, also piled meat). 疊 therefore expresses the tautological idea of pile up + pile → *pile/fold* an object to a number of layers → *fold up*; *tatami* → *put an end to* (← fold and put away after using).
[Full Kanji Etymology List]