Doubt

1a. There is little doubt the documents are fake.
1b. There is little doubt at all the documents are fake.
1c. There is no doubt the documents are fake.
Please correct the above.
Do all these sentences mean the same?
Thanks.

No corrections. The meanings differ.

1a/1b - there is some doubt.
1b emphasises that the amount of doubt is very small a little more than 1a does.

1c - there is no doubt.

Beeesneees,

  1. There is a little doubt the documents are fake.
  2. There is a little doubt at all the documents are fake.
    If you add ‘a’ before ‘little’ what are the meanings of these sentences?
    Please comment.
    Thanks.

It makes a bit of a mess of 1, because it is then saying that there is a slight doubt that they are fake, so they could be genuine. You would expect:
There is a little doubt the documents are genuine. - indicating that there is a slight chance they are fake.

2 doesn’t make sense with the addition of the article.