How can I align 2 set of strings in checkedlistbox item in WPF using C#?

One of the solutions could be:
Given the text of checkboxlist item are from two different sources, havea predefined length of text (say 40) and then put strings from left to right (index 0) and put the another data string from end (index length). Fill in the middle left space with space.

This way, you would have a view as above.

PS: if you have defined lenghts of the two strings, it would be easier to optimize. Base here is to play with the length.

BTW, for above, you can make use of string concatenation and PadRight[^]/Padleft[^] methods with defined lengths.

UPDATE:
A quick attempt on .NET Fiddle: Fixed length of text can have padleft/padright setup[^]
It shows:

String first ="firstone";
String second ="secondone";
String needed = first.PadRight(25,' ') + second.PadLeft(25, ' ');
Console.WriteLine(needed);
Console.WriteLine("lenght: "+ needed.Length);

//Output as:
firstone                                 secondone
lenght: 50