Open your first page.
On the Tools menu, click Compare and Merge Documents.
Select the document that you want to compare to the copy that is currently open.
Click the arrow next to Merge, and then do one of the following:
To display the results of the comparison in the selected document, click Merge.
To display the results in the document that is currently open, click Merge into current document.
To display the results in a new document, click Merge into new document.
Notes
To ensure the best possible merge results, make sure that the Store random number to improve merge accuracy check box is selected on the Security tab of the Options dialog box (click Options on the Tools menu).