Other than the second antenna you should also be thinking about combining the signals from two antennas. When you combine a VHF and UHF antenna, you will need a combiner. Don't use cheap splitter/combiner. Examples are
AD VHF/UHF Combiner
Leviton UHF/VHF Signal Combiner C5159
Axis HE8226
For the antenna selection others should be able to comment.
If you are combining two antennas aimed at two different markets, then it is better to use the same antenna models and point them in different directions. The cables should also be cut to the same length before they are joined. This will minimize the lag and phase cancellation. In such a case, you can use a standard splitter/combiner. However you are not in that situation as you need to combine a VHF with UHF.