[cem] imbalance measure (L1) question

Hello everyone, Can anyone help me understand why imbalance measure (L1) for "mat" function is different from imbalance measure obtained from matched dataset using "imbalance" function? Initially when I ran "mat" function, it gave me imbalance measure (L1) of 0.727 with 171 matched control and 116 matched treatment. I subset those matches from the original dataset and ran "imbalance" function and it gave me L1=0.825. I'm not sure why it's giving me a different L1 value. Thank you