Your first approach is copying all the axes children from one axes to another, which is not copying the axes itself (just its children), so it is not getting the title and labels (because those are properties on the axes).
Your second approach is trying to copy all the figure's children, which includes the toolbar and figure menus, so that is going a little overboard.
You could try copyobj on just the figure's children into a new figure.
f = figure;
ax1 = copyobj(c.Children, f);
ax2 = copyobj(k.Children, f);
Now you will likely need to set the position on the children in the new figure, so they don't overlap. Assuming each starting figure has a single axes, you can also add existing axes to a subplot like this:
subplot(1, 2, 1, ax1)
subplot(1, 2, 2, ax2)
If that doesn't work, we would need more details about your starting figures. Do they have legends or colorbars? How many axes are in each figure?