In the latest episode of “Serving Russia!” – a series of popular Russian defence reports by Telekanal Zvezda(see below) at 1:55 minute mark, two 96L6 acquisition radars can be seen about 3O meters apart from one another at what is most probably Russia’s Hmeimim (Khmeimim) airbase in Syria.
Official Russian marketing literature refers to 96L6 as an all-altitude detector(VVO). Its development started in mid 80’s and it was conceived as an acquisition radar for S-400 air-defence system(ADS), with an option of integration with late versions of the S-300 ADS. Operating in C-band, 96L6’s multi-phased array is able to track target coordinates at ranges of up to 300km.
Having two high-altitude acquisition radars with a combined ability to track up to 200 targets with their respective azimuth, elevation and range parameters seems like an overkill for just one S-400 battery. A single S-400 battery consists of between four and eight transporter erector launches or TELs, with four missiles each. Some sources claim that one 96L6 within a single command section, can be used to provide a target data for up to eight(!) S-400 or S-300PMU series batteries.
One obvious explanation for the presence of two 96L6 radars might be that there are more long-range air-defence batteries networked in, be it Russian or Syrian.
It mighty also be the case that 96L6s are used for both air traffic control (ATC) and air-defence acquisition and tracking over at Hmeimim. Or it might simply be that they are used alternately, allowing for the respective maintenance of the units and backup in case of malfunction of one of the two. The footage above in part supports this explanation since array of 96L6 on the right is not revolving, which doesn’t necessarily mean that it is turned off, simply that its coverage is way below optimal, probably at about 120° azimuth.
None of the above explanations for the presence of two 96L6 radar systems at Hmeimim air base exclude one another, therefore it might be all of the above.