title: Find partially duplicated lines, keep first instance and leave the rest untouched
body: <p>I've tried several things with RegEx in Notepad++, but I'm not even sure if it's even possible. I tried one or two things with PowerShell as well and nothing works.</p>
  
  <p>Data comes like this:</p>
  
  <pre>
  007.130.0001;E2
  007.130.0001;E4
  007.130.0001;M4 20.1
  007.130.0001;M4 20.1 NX
  007.130.0002;E2
  007.130.0002;E4
  007.130.0002;M2_duplicate
  007.130.0002;M4 20.1
  007.130.0002;M4 20.1 NX
  007.130.0008;M4 20.1 NX
  007.130.0008;M4 20.3_M4 25.3
  007.130.0008;M4 20.3_M4 25.3 NX
  011.130.0124;E-Serie_duplicate
  011.130.0124;M4 20.1
  011.130.0124;M4 20.1 NX
  </pre>
  
  <p>and I want it like that (Option A):</p>
  
  <pre>
  007.130.0001;E2
  ;E4
  ;M4 20.1
  ;M4 20.1 NX
  007.130.0002;E2
  ;E4
  ;M2_duplicate
  ;M4 20.1
  ;M4 20.1 NX
  007.130.0008;M4 20.1 NX
  ;M4 20.3_M4 25.3
  ;M4 20.3_M4 25.3 NX
  011.130.0124;E-Serie_duplicate
  ;M4 20.1
  ;M4 20.1 NX
  </pre>
  
  <p>or that (Option B):</p>
  
  <pre>
  007.130.0001;E2;E4;M4 20.1;M4 20.1 NX
  007.130.0002;E2;E4;M2_duplicate;M4 20.1;M4 20.1 NX
  007.130.0008;M4 20.1 NX;M4 20.3_M4 25.3;M4 20.3_M4 25.3 NX
  011.130.0124;E-Serie_duplicate;M4 20.1;M4 20.1 NX
  </pre>
  
  <p>So basically I want to split a line at a special character (<code>;</code>) and check the first part for duplicates with the next line, deleting all of them but the first and keep the rest of the line untouched.</p>
  
  <p>The closest I've got was this RegEx:</p>
  
  <pre><code>Find: ^([^;]+;).+\R(.*?\1.+(?:\R|$))+
  Replace: \2
  </code></pre>
  
  <p>But then I'll end up with this: </p>
  
  <pre><code>007.130.0001;M4 20.1 NX
  007.130.0002;M4 20.1 NX
  007.130.0008;M4 20.3_M4 25.3 NX
  011.130.0124;M4 20.1 NX
  </code></pre>