In the case you come across duplicate records. Use Search parameters to bring up both records, then select the boxes of the records you want to merge. 


The data from the first record you select when merging will be kept in the record once merged.




If any fields are blank in the first record then the data from the subsequent record (if any) will populate in the merged record. 


If there is data in a field of the first record and there is also data in a subsequent record in the same field then the subsequent records data will be erased. 


In this example the first record with data showing "andrew.smith@outlook.com" will remain in the merged record and the second record field asmith1234@outlook.com will be erased.  




Then right click anywhere in the grid to bring up options and click on "Merge".



This will merge both records and bring you to the combined record profile. 



Would you like to know the different levels of Access that Users can have? Have a look at this article here.