Removing Duplicated Substrings

I understand that the following question may not be best practice.

I have a table that has the following structure, the keyword column and title column concat into the mashup column.

+------------+------------+-----------------------+
| Keyword    | Title      | Mashup                |
+------------+------------+-----------------------+
| Green      | Green      | Green Green           |
| Green      | Watermelon | Green Watermelon      |
| Watermelon | Watermelon | Watermelon Watermelon |
+------------+------------+-----------------------+

I would like to know if there is a way of "deduping" the string. So my table will look more like the below:

+------------+------------+-----------------------+
| Keyword    | Title      | Mashup                |
+------------+------------+-----------------------+
| Green      | Green      | Green                 |
| Green      | Watermelon | Green Watermelon      |
| Watermelon | Watermelon | Watermelon            |
+------------+------------+-----------------------+

Is this possible? I can't seem to find a solution. Thanks!