Kane/Keane/Ledwith

I have hit a brick wall and would love some help if anyone is up to a real challenge! 

In the 1901 census I have my great grandfather and family living in Henfield, Glen Lough:

Keane Peter - 45 - Head of Family

Mary Ellen - 36 - wife

Maggie - 15  daughter

Michael - 12 son

Patrick - 10 son

Owen - 5  son

Mary E - 6 months daughter

As per the 1885 marriage cert between Peter Keane and Mary Ellen Ledwith the fathers are listed as Denis Kane and Patrick Ledwith.

Searching for a Denis Kane, I found a family also living nearby in Stongaluggan, Glen Lough with very similar names:

Keane Denis - 70 - Head of Family

Margret - 69 - Wife

Peter 41 Son

Mary 39 Daughter

Margret 31 Daughter

James 28 Son

How possible is it that someone would name two of their sons the same name?

Where can I keep looking? I have searched through church records and can not find anything to help me know who "my" Denis Kane/Keane is.

Any suggestions?