Help with Formula

[Barbiro]

I was asked to analyze a very LONG list for duplicates. I tried using "Conditional Formatting" but the problem with that is that it also highlights "triplicates, etc." and NOT ONLY "duplicates" which is what I want. What I need is this: If the B2 column contains 2 identical "duplicates" (usually one below the others as in "2846 and 3445"), then I want on the C Column for it to say "True". I want the formula to skip triplicates, etc... exclusively pointing out sets of two. Thanks for any help you guys can give me on this... totally appreciated.

2846
2846
2930
2930
2930
2930
3445
3445


2778
2778
2778
2778
2778
2778