LaTeX - Proper vertical spacing on multi-line parboxes with multicols

Answer 1

1) Define your macros, for example, \colparbox and \Alt.

2) Look the following code.

\def\colparbox#1{\strut \par \vskip -\baselineskip \nointerlineskip
   \parbox{\columnwidth}{\strut\ignorespaces#1\unskip\strut}\par}

\def\Alt{\hspace{1em} \textit{Alternative:} }

\begin{multicols}{2} 
\RaggedRight 
Alpha\\ 
Beta\\ 
\colparbox{ Zeta\\ \Alt Upsilon } 
\colparbox{ Gamma\\ \Alt Lambda } 
Epsilon\\ 
Omega\\ 
\colparbox{ Omicron\\ \Alt Upsilon } 
Kappa\\ 
\colparbox{ Zeta\\ \Alt Upsilon } 
\colparbox{ Zeta\\ \Alt Upsilon } 
Alpha\\ 
Beta\\ 
\colparbox{ Zeta\\ \Alt Upsilon } 
\colparbox{ Gamma\\ \Alt Lambda } 
Epsilon\\ 
Omega\\ 
\colparbox{ Omicron\\ \Alt Upsilon } 
Kappa\\ 
\colparbox{ Zeta\\ \Alt Upsilon } 
\colparbox{ Zeta\\ \Alt Upsilon } 
Sigma\\ 
Delta\\ 
\end{multicols}