Data type/structure for merging data in a datagridview

I开发者_运维技巧 have a currently have the user input a tag, I get the values for that tag (which are a timestamp/value pair) into a datagridview. I'd like the option to add multiple tags which would each get a column in the datagridview with only a single timestamp column, which would hold merged timestamps.

I currently have this:

Tag = ...

   ...//TagVals are the values (timestamp/value pairs) for the tag
   TagVals = tag.Values; //pseudo
   foreach(var val in TagVals)
   {
       object[] vals = new object[2];
       vals[0] = val.timestamp;
       vals[1] = val.value;
       datagridview1.Rows.Add(vals)
   }

But i'd like to have multiple tags in the same datagridview, so I need something like this:

foreach(var tag in Tags)
{
   ...//TagVals are the values (timestamp/value pairs) for the tag
   TagVals = tag.Values; //pseudo
   foreach(var val in TagVals)
   {
       //?? object[] vals = new object[2];
       //?? vals[0] = val.timestamp;
       //?? vals[1] = val.value;
       //?? datagridview1.Rows.Add(vals)
   }
 }

assuming the TagVals contain these timestamp value pairs (where the 1.x values are coming from the first tag, and the 2.x values are coming from the second tag):

2:00  | 1.1
2:20  | 1.2
2:40  | 1.3
2:00  | 2.1
2:30  | 2.2
2:40  | 2.3
2:50  | 2.4

I want my datagridview to look like this:

2:00  |  1.1  |  2.1
2:20  |  1.2  |  
2:30  |       |  2.1
2:40  |  1.3  |  2.3
2:50  |       |  2.4

What is the best data structure/type to use to hold these values, and to merge them into the datagrid view?