Multiple Pitch Accents

I tried using an anki plugin (https://ankiweb.net/shared/info/932119536) to display the pitch accent of words I'm learning. Some of the words I tried entering showed multiple possibilities for the same word. For example, it shows that 二つ rises on た, but may or may not drop つ. Its the same with 三つ. 夜間 can either start high and drop after や, or rise on か.

I am looking for the "officially correct" accent of Tokyo Japanese. I saw an official pitch-accent book by NHK somewhere. I'm thinking about something like that.

So my question is, do some words really have more than one possible accent? I know the accent can be modified for any word by the situation, emotion, etc..., but will an official pitch-accent dictionary list multiple accents. The plugin I used does it automatically (although it claims they originated from NHK) so I'm worried there could be errors.

Lastly, I do not plan to memorize the pitch-accent for every single word in Japanese. I'm only using this to get the basics.

I know that was off topic, but I thought I should add it in for the sake of those who pop up out of nowhere to criticize study habits:)

Answer

I have a copy of the 新明解日本語アクセント辞典 dictionary (my detailed review of it) somewhere and I remember seeing multiple entries for some of the words.

While I have looked up a few words in it and also utilized Japanese electronic dictionaries that have audio samples for certain words, overall I've found that I learn more about pitches from paying careful attention when listening to things like podcasts and other media. However, if you were literally trying to get every one of your words to have correct pitch, I think the above book could come in handy.

When you hear a common word you think you might use yourself (i.e. 英語）, you can try and repeat what you just heard, or rewind and re-listen to hear the exact pitch pattern used.

If you are serious about learning Japanese pitch accent, you might want to learn some related rules like how pitch of certain words changes when they are in combination with others, or how a high accent can effect subsequent word(s). Also, learning the common pitch patterns also helps you narrow down what to hear for (for example, you will never hear high-low-high in a word, as far as I know).

Also, regarding your comment that pitches can change based on emotion - I feel that while there can be a change in emphasis, loudness, or relative pitches, the overall pattern doesn't change that much, even if someone is agitated or upset.