DesignMerge may merge unexpected records if the data file is not in a plain delimited text file format, if there are empty lines in the data file, if the document's DDF does not have appropriate settings, if variable links are not assigned to appropriate sequence numbers, or if inappropriate settings are selected for a merge session. To determine why your job is merging unexpectedly, follow these steps:

First, open the data file in a plain text editor (for example, BBEdit or Notepad++) and confirm the following:

• Confirm the file is in a plain delimited text file format.
• Examine the file for extra empty lines and look for extra Line Ending characters, which may be displayed by your text editing application as an unknown character (for example, as an "¿"). If you see extra empty lines, remove them.
• Determine which character is being used as a field delimiter.
• Examine the file to see if any quote marks are being used as a text qualifier.

Next, confirm the following settings that are displayed on the document's Edit Data Source Definition dialog. To display this dialog, first open the document. Next, open DesignMerge menu, choose Setup > Data Source Definitions. Then, click on the Edit button. 

• Confirm the File Origin setting is set to Auto-Detect or matches the file origin of the database file. 
• Confirm the Field Delimiter setting matches which character is being used in the database file as a Field Delimiter.
• Confirm the Text Qualifier setting is accurate. For more information about selecting the correct Text Qualifier setting, see the Unexpected quote mark or inch mark in Links? Knowledgebase Article.

Last, confirm the variable links in your document are sequenced properly and that you are applying an appropriate Records selection for the merge session: 

• To confirm which sequence numbers are assigned to variable links in your document, open the document and then run a Variable Link Report. For example, if you would like to merge one record at a time into the document, confirm all of the variable links are assigned to sequence number 1. If you would like to merge a multi-up document, confirm the variable links have been assigned to consecutive sequence numbers. To re-sequence variable links in the document, close the report and then apply either Change Seq. # or Sequence Page Items from the DesignMerge menu, whichever is appropriate for the content you have currently selected in the document. 
• The Records selections are displayed on the DesignMerge (merge) dialog (DesignMerge > Merge). If you are merging a one-up document, confirm you are choosing Step by: 1. If you are merging a multi-up document, confirm you are choosing to Step By the largest sequence number assigned to a variable link in the document or choosing a Cut & Stack sequence mode. 

For more information about setting up and editing a DDF, running a Variable Link Report, sequencing variable links in a document, and selecting options for a merge session, see DesignMerge Documentation.