October has a duplicate day

[pedrosino]

Sorry, I couldn't find a better title.
I'm in Brazil, GMT -3, and seems like every month of october has a weird behaviour. See gif and image below

Basically the 3rd or 4th saturday has a "twin" to its right, and clicking on the following sunday is problematic.
Clicking on the saturday highlights both cells.
Clicking on the following sunday highlights the correct day, but the text doesn't change.
Dates saved as that sunday appear as saturday.
I had another user (in Mexico) face this. People in USA and Europe don't seem to have the same problem.

Any idea? Any detail I should also give?

[zpaulovics]

I will have some time to deal with it on the second half of the week. Also planning to update the JavaScript library version that days.

[jfly]

Any update here? Thanks!