jcjeant
Read the BEA document again: it doesn't say that invalid speed condition lasted less than one minute, it says that inconsistency between LH speed display and ISIS speed display lasted less than one minute.
Note: The inconsistency between the speeds displayed on the left side and on the ISIS lasted a little less than one minute.
(my bold)
We can probably infer that further invalid speed conditions were equally reported on LH panel and on ISIS.