Why does Shift dot take two hands when dot takes one?

Are you using a U.S. keyboard?

Is the NumLock on your numeric keypad on or off?

I use the period key to enter a dot on the already-entered (and selected) note. To remove it, I select the dotted note, and replace it with an undotted one (Opt-Numpad key.)

@Adrian Verkouteren-Mike Rosen: My pc is obviously reacting weird. After a reboot augmenting a note by using only the period key works. I also noticed that using the period key more than once on a selected note adds more dots, however after a few minutes this feature is gone (??). What would be the fastest way to augment a note with (one and) two dots? And how can this process be reversed (talking off augmentation dots) without having to replace it by an undotted one? Thanks!

From the user's manual:

In Simple Entry, if you click on the dotted note with the original note value, the dot(s) will disappear.

In Speedy, a similar result if you select the dotted note and press the key for the original, undotted rhythm.

For me, the fastest way to dot a note once or twice is to hit the period key as I enter the notes, using the QWERTY keyboard and number pad. But it may not be fastest for you. How are you entering notes?

@Adrian: Thanks for your reply. Ok, I had hoped there would be a quicker way to remove augmentation dots. Forgot to mention: Hitting a numpad key once or twice does not change/remove an augmentation (page 11 of the English Quick Guide) in my case. Could that have anything to do with general settings? Thanks!

@Mike: Thanks for your reply. Hitting the period key more than once doesn't do anything on my pc, it just works for one dot only. I trying to enter notes with the pc keyboard. It seems the fastest way but still *a lot* slower than the notation program I am used to.

Every program is slower than the one you learned on, until you really learn the ins and outs!

i don't know why the double dot doesn't work for you, but I'm not familiar with the Windows side. 

Perhaps this depends on how one's system and Finale have been configured, but clicking the period twice (on either the NumberPad or the QWERTY keyboard) gives me two dots; it does not cancel one out, so my workflow has developed accordingly.