Wrong time reported in Views

Time tracker entries on certain nodes appear with wrong values in Views
I did not found any hints about what can trigger this very strange behaviour

- The value appears multiply by an integer factor (I got x2 and x10 to date)
- The problem appears in the time_tracker_report views as provided : the sum of all entries at the bottom of the detailed list is wrong
- the problem does not show up in another Views Calc Table I set using GroupBy Field : the sum of the consolided entries per node I created is OK
- The time_tracker_entry table in the database is OK

I can solve the problem by cloning the node and recreating the entries.

Another way of explaining what I observe:
It looks like Time tracker attached an integer to the node, defaulting to 1 and then uses it for multiplying the duration value when exposing the duration field in Views. The original value is correctly passed programmatically.