Hello,
We say
1) It is uncommon to say…
2) It is not common to say…
What about “It is not uncommon to say…”?
Is not uncommon for confirmation? If the answer is yes, is not uncommon for the confirmation of the affirmative or for the confirmation of the negative? What exactely the meaning of It is not uncommon to say…?
Many thanks
It is not uncommon for people to say it is not uncommon. 
This is a double negative. However It is not uncommon does not mean the same thing as It is common.
It is not uncommon. means not rare or not unusual. It means it is not common, but not extremely rare either.
It’s a matter of degree. On a scale of 0-10:
0 - never happens
10 - happens constantly
One person might say that 8 is common, and 1 is uncommon. Someone might say that 3-4 is not uncommon, but it’s not common either.
Thank you very much NearlyNapping.
You are right. It is not uncommon can cause confusion. Simply, It is uncommon= it is rare. No need for using it is not uncommon.
Hi Mona, I’m afraid you didn’t quite understand what NearlyNapping gave you. The phrase “it’s not uncommon” to is a fixed expression (or ‘strong collocation’) that is commonly used in modern English, and it has a specific meaning, so you can’t just replace it with another phrase.
Excuse me Sir Torsten, what is its specific meaning?