Any extra considerations for different wavelength same band antennas on car?

[K5_489]

I know when having multiple same band antennas on a vehicle that you want a minimum of 1/4 wave separation between the two, with more is better, and this is based on the wavelength of the frequencies being used. 

Does this get altered with using different length antennas on the same band, or any other things that should be kept in mind if I were to install a 1/2 wave 2M, 5/8 wave 70CM antenna together with an existing 1/4 wave 2M antenna? 

In my head, it doesn't seem like it should make a difference as 1/4 wave of 2M is the same regardless of antenna length, but I keep thinking of different radiation angles, confusing myself, and Google isn't helping... I'm pretty sure I'm just overthinking this, but wanted some confirmation either way. 

Oh, and in case someone wonders why - I currently have a FT-100 in the truck.  I'm adding one of my Kenwood TM-D710 radios, and I figure two antennas better than one, and no worries about a failed duplexer back feeding the other radio.  Plus a 2nd antenna is cheaper 😅