Only Show Unique Entries in Text Field

Yes you can, but if you are showing a lot of columns it could be difficult. If any single column is aggregated then the others will only show unique values. 

To test it simple just add two columns such as agent and count of `somethingelse`

If this is your data:

Agent    Amount  Product
Jim      50      Box
Jim      60      Bag
Jim      40      Box
Jenny    90      Box
Jenny    80      Box

The simplest card will look like this:

Total = SUM(`Amount`)

Agent    Total
Jim      150
Jenny    170

It only shows the Agent once because of the aggregated `Total` column. However if you add other columns they will affect it. If the card shows `Product` it will look like this:

Agent    Product   Total
Jim      Box       90
Jim      Bag       60
Jenny    Box       170

Jim shows twice because the combination of Jim+Product is unique. The table card will make sure all unique values are shown.

You'll have to play with it to get the list you want but if the only non-aggregated column is `Agent` then you should only get each agent's name once.

Extra Thought:

In a table card you have the ability to hide columns. If you don't want the second column to show, so just a list of Agents only with no other columns, then you can hide it via Chart Properties > General > Hide Columns