I only got the double with my last guess. If you had guessed that letter earlier did it not give any indication that it appeared twice? If so, surely it still showed as an available letter in the keypad bit?
It would be slightly easier once you have a couple of letters if you could type them in and leave others blank to help visualise it more easily.
I had no letters with my first guess
Second guess I had the 4th letter from the correct word, but the word I guessed, it was the 5th letter in that so showed up yellow
3rd guess I got 3 letters, 2 in the correct position and one in the wrong position. From the correct word, my word had the first, 3rd and 4th letters, but only the 3rd and 4th in the right position. The other correct letter I had in the 2nd position.
4th guess, all 3 of my letters in the correct position. 1, 3 and 4. No indication there could've been a double letter.