I have a list of objects: IList<O>
O has several properties but only two of them are relevant: Date and Duration

I want to "split" the list into several lists that contain only the objects that have matching Date and Duration Properties.

Example:

InitialList:
0- Date==1, Duration==7
1- Date==1, Duration==7
2- Date==2, Duration==7
3- Date==2, Duration==7
4- Date==2, Duration==14
5- Date==2, Duration==14

Desired result:
IList<IList<O>>:
0-
0- Date==1, Duration==7
1- Date==1, Duration==7
1-
0- Date==2, Duration==7
1- Date==2, Duration==7
2-
0- Date==2, Duration==14
1- Date==2, Duration==14

i know this can be done with some linq selects but am not sure how.
thanks for the help.