To put two companies and locations for the same job title, you could use the penultimate argument of \cventry to hold information about the second company and location.
Depending on the style you are using, you will need to set formatting manually accordingly inside that argument, i.e. for the classic or casual style:
Also, use a scalable modern font which scales well to lower font sizes (eg: lmodern, kpfonts). However, in general, it is not recommended to not use such small font sizes in the interest of readability.