The result is very strange with VisitsSummary.getUniqueVisitors

Support & Bugs
1

I want to get the UV with the following API
first way, by week

http://demo.piwik.org/?module=API&method=VisitsSummary.getUniqueVisitors&idSite=7&period=week&date=2016-06-06&format=xml&token_auth=anonymous

secend way ,by day
http://demo.piwik.org/?module=API&method=VisitsSummary.getUniqueVisitors&idSite=7&period=day&date=2016-06-06,2016-06-12&format=xml&token_auth=anonymous

the result of first way(by week: date=2016-06-06) is:
4097

the result of secend way(by day: date=2016-06-06,2016-06-12) is:

775
841
800
784
655
281
282

total result is 4418

in my opinion,the result should be the same, but in fact it is not.
plz explain the reason/ who can tell me why~~~

2

help! help! help! help me!

3

The sum of “Unique visitors” is the not the same as “Unique visitors” across the week, because a same visitor may visit many times over the week but will be only counted once.