Concatenating cells and removing duplicates

I am trying to concatenate (join) three column. As there is some data in one column that is the same as one of the other columns I need to come up with a formula that will Count one of them.

for example: Cell H2 has "organic decline" and Cell J2 has "Organic Decline". I a am looking for Column K - where the formula will be, to have just one of these populating it

Thanks in advance