.Net regex - extract data from one of two groups
<p>Given two groups of data below and the limitation of .Net regex, no subtitution and no programmatic means, how can I capture data (Last Name or First Name) from the User Information group but not the Invoice Information group? When I construct a regex two results always occur.</p>

<pre><code>User Information:
Title:                Product Specialist
Last Name:            Smithson
First Name:           Robert
Invoice Information: 
Title:                Buyer
Last Name:            Moneypenny
First Name:           Penelope
</code></pre>

<p>I can easily extract data from the Invoice group with this expression: <code>(?&lt;=Invoice\sInformation\:(.*\r\n)*Last\sName\:\s*).*</code>, but the problem is the first group.</p>