It looks like they are in very similar orbits in both space and time, and are probably that way so that the datalink between the two can be demonstrated and put through tests along with links to ground stations.
If that is so, what technology provides link between satellites? For example, if microwaves are used, what band? If the link is optical, is it visible or infrared or UV. If in-between (e.g. THz) then roughly what frequency?
The question What technology will SpaceX's StarLink satellites most likely use for sat-to-sat linking? asks about the plan for the final Starlink constellation. Here I'm just asking about Tintin A and B.
43217 from N2YO.com at about
2019-03-07 at 04:50 UTC
Source: Gunter's Space Page