20.26 swimming time is way off

Hello,

I did two 50 m in about 1'51" and the watch tell me I have done it in 1'25.

All informations are strange : the duration is written as 1:51,3, the moving time as 1:24,6 and total time as 3:13,1 (and I started the timer when starting to swim and ended it at the end of the 100 m).

connect.garmin.com/.../16974145684