Chronologic team screwed up a lot with this issue. Two tokens and same functionality, so price is divided by two. YESTERDAY tokens should be burnt.
Time is a phisical quantity. Chronologic concept is not just about math and numbers.
In my opinion we have 2 different contracts able to be used in different context.
I can imagine a different usage both for Yesterday and for Day.
Contracts are the same except difference in chronopower value.