What does this tell me?

[Rdmclure]

I have a match on a segment of chromosome 5 with someone.
I have a match with a 2nd cousin on a larger segment of the same chromosome.The first segment is completely within the one for my cousin.
When I do an "In common with" search on the first person my 2nd cousin is not shown.
Does this mean my cousin is not a match for the other person?
Thanks

[prairielad]

I have a match on a segment of chromosome 5 with someone.
I have a match with a 2nd cousin on a larger segment of the same chromosome.The first segment is completely within the one for my cousin.
When I do an "In common with" search on the first person my 2nd cousin is not shown.
Does this mean my cousin is not a match for the other person?
Thanks

Yes it means this match is not on your 2nd cousins match list, but that is not saying you match each through separate lines. It is a little more complicated then that.

What is this segments cM and SNP value you share with this match on chromosome 5? What is the total cM value of DNA you share with this match?

When you run the In Common with this match how many people on that list is shared with your 2nd cousin list when you compare it to their list when you run In common with on them?

Do you and these matches utilize Gedmatch?

[John McCoy]

Unless the segments involved are too small to be significant, and assuming that the FTDNA utilities are working correctly, the fact that you have two matches for the same section of a chromosome, but they don't match each other, simply means that one of those matches comes from your paternal ancestry, and the other from your maternal ancestry. You have two copies of each autosome, one from your mother, the other from your father. You probably know which side of the family your "cousin" represents, and that may allow you to establish that the other match is related to your other parent.

[prairielad]

Unless the segments involved are too small to be significant, and assuming that the FTDNA utilities are working correctly, the fact that you have two matches for the same section of a chromosome, but they don't match each other, simply means that one of those matches comes from your paternal ancestry, and the other from your maternal ancestry. You have two copies of each autosome, one from your mother, the other from your father. You probably know which side of the family your "cousin" represents, and that may allow you to establish that the other match is related to your other parent.

I know John McCoy stated the unless, but do not assume one is paternal and one is maternal due to the fact that they are not on each others match list and overlap you on same segment.

This segment may be present(matching) in both this match and your cousin, but if your cousin and this match do not share at least 20cM in DNA in total with each other, algorithm will reject them as a match to each other.

This is where Gedmatch comes in handy using their one to one compare between these two kits if both utilize Gedmatch.
or manually comparing Raw Data files with David Pikes Utilities if these kits will share their Raw Data with you.

[Rdmclure]

Thanks everyone who replied.