If you are certain that two separate titles listed on IMDb refer to the same film/show and need to be consolidated into the same listing, please follow these instructions to request the merge.
To submit a correction, you should use the 'Title Correction' option to change the title of one to the second. For example, if you know that the pages for Untitled XYZ Project (2006) and The ABC Movie (2006) refer to the same film, you would go to the page for Untitled XYZ Project (2006), click on the Edit Page button at the bottom of the page, select the 'Title Correction' option and change the title of the film to The ABC Movie (2006). This will result in a merge of the two titles.
1) You need to submit the correction so that the old/outdated/incorrect title is changed to the current/correct title, not the other way around. Go to the page for the old/incorrect title and enter the title of the second listing as the correct title. You'll need to enter the title exactly as it appears in the second listing (you should get a message warning you that the second title already exists: this is ok).
2) Please verify that the two titles really refer to the same film/show. Don't be confused by similarities or by different films/programs that just happen to share the same title. For example True Grit (1969) is not the same as True Grit (2010). The first is the film starring John Wayne, the second is the 2010 Coen brothers film adaptation of the same novel. It's a good idea to check the connections section, to see if one title is a remake of the other or if there is another connection which shows how the titles are different.