This doesn't appear to be a name split situation, since the two people already have separate pages. Rather, it looks like some of John Bentley (I)'s credits have been mistakenly assigned to John Eric Bentley.
If so, here is how to fix that:
Go to the page of John Eric Bentley and click "Edit page".
On the next screen, on the Actor Credits line, select "Correct/Delete". Scroll down and click "Continue".
On the next screen, you will see all the actor credits currently assigned to John Eric Bentley. To the left of every one that actually belongs to John Bentley (I), select "Correct". Leave all the others as "Keep". Then, at the lower right of the credits listing, check the box marked "Show name?". Click "Check these updates".
On the next screen, you will see that you can edit the name for each of the credits you marked to "Correct". In the Name box, change the name to:
Bentley, John (I)
In addition, if there is an (as John Bentley) attribute on the same line, remove it. (Since the credit belongs to John Bentley, there's no need for an attribute to state that he was credited by his regular name.)
For each correction you make, check the box marked "provide an explanation to assist in processing this change".
Click "Check these updates".
On the next screen, there will be an explanation box under each credit you are correcting. Enter an explanation as to how you know that the role was played by John Bentley (I) rather than John Eric Bentley. You can enter the same explanation every time if applicable. Click "Re-check these updates".
On the next screen, your corrections should appear with a green background, and you should be able to click "Submit these updates".
Good luck!
