Get copy of cache item?

[ceestand]

I am having a weird (to me at least) problem retrieving a copy of an item in the Cache.

I do something like this:

DataTable ToBeInserted = FunctionThatReturnsDataTable();
Cache.Insert("CacheTable", ToBeInserted);
public DataTable function()
{
DataTable Results = (DataTable)Cache[CacheTable];
Results.Columns.Add("Rank");
return Results;
}

On the second time running the function, I get an exception that the column "Rank" is already part of the table.

Shouldn't "Results" be a new DataTable instance? I'm unintentionally adding the column to the Cached item. I just want a copy of the cached datatable to alter and return. When I run the function, I want to create the Results table all over again and modify it without altering the cached datatable.

Any ideas?

[ceestand]

Anyone have a guess?

Bueller...?