TheOptimizationIdiot - 10:46 pm on Apr 11, 2013 (gmt 0)
I missed that...
In that case, I'd redirect the .net straight across to the .com and wait until the traffic level of the .com was about the same as the .net and .com combined. Then I'd change the URL structure of the .com.
In answer to your question, no it does not require 2 redirects. It requires you to change where the redirects on the .net point, because if you can redirect the current .com locations to the new .com location and the URLs on the .com and .net are the same, then you can as easily redirect the .net to the same new locations on the .com.
In the .com .htaccess:
RewriteRule ^old-location-on-the-dot-com\.ext$ http://www.example.com/new-location-on-the-dot-com.ext [R=301,L]
In the .net .htaccess:
RewriteRule ^old-location-on-the-dot-net\.ext$ http://www.example.com/new-location-on-the-dot-com.ext [R=301,L]
Regular expressions may help you avoid having one redirect for every single page on either site, but there's no guarantee and that's a topic for the Apache Forum linked below.
All you have to do to avoid multiple redirects is set the .net to redirect to the new location on the .com when you set the .com to redirect to the new location on the .com. If the URLs are the same and you can redirect one to the new location, then you can redirect both directly to the new location.
If you don't know how or can't figure it out, I'd recommend either spending some time in the Apache Forum [webmasterworld.com] and learning or hiring a professional.