You can do it without cell2mat. If you want to get specific columns, use one of these assignment options to get your (34490x2) double array:
C = {randi(10,30,20)}; % Create Data (Cell Array)
D = C{:}(:,1:2); % Get Columns 1 & 2 As Double Array
D = C{:}(:,[10 15]); % Alternative: Get Any 2 Columns (Here 10 & 15)
Alternatively, if you have more than one array in your cell:
C = {randi(10,30,20) randi(10,30,20)}; % Create Data (Cell Array)
D = C{1}(:,1:2); % Get Colimns 1 & 2 Of Array 1 As Double Array
D = C{2}(:,[10 15]); % Alternative: Get Any 2 Columns Of Array 2
