Yes, there is a function that can help you with this. Instead of using the LOOKUP function, you can use the INDEX and MATCH functions together to retrieve multiple elements for one lookup value.

Here are the steps to do this:

1. Select the cell where you want to display the results.
2. Type the following formula:
   Formula:

   =INDEX(range,MATCH(lookup_value,lookup_range,0)) 

3. Replace "range" with the range of cells that contains the values you want to retrieve.
4. Replace "lookup_value" with the value you want to look up.
5. Replace "lookup_range" with the range of cells that contains the lookup values.
6. Press Ctrl+Shift+Enter to enter the formula as an array formula.

This formula will return an array of values that match the lookup value. If there are no matches, it will return an error message.

If you just want to know if there are duplicate matches, you can use the COUNTIF function. Here are the steps to do this:

1. Select the cell where you want to display the results.
2. Type the following formula:
   Formula:

   =COUNTIF(range,lookup_value) 

3. Replace "range" with the range of cells that contains the values you want to check for duplicates.
4. Replace "lookup_value" with the value you want to look up.
5. Press Enter to enter the formula.

This formula will return the number of times the lookup value appears in the range. If it returns a number greater than 1, it means there are duplicate matches.