The following diagram (which I've adapted from Chapter 7 of "Exploring Black Holes" by Taylor, Wheeler & Bertschinger) shows the radial world-line of a free-falling observer into a Schwarzschild black hole (labelled as "world line of a raindrop") and the null geodesics followed by light emitted by that observer, both radially inwards and radially outwards (labelled as ingoing and outgoing flashes). The diagram uses Gullstrand-Painleve coordinates $r, T$.
I have added a further (red) worldline, which represents the trajectory of another free-falling observer (let us call them observer 2) that crosses the event horizon (at $r/M=2$) at a larger value of $T$. Observer 2 is capable of receiving light signals from the first observer up to point E, at which point, the outwardly directed null geodesic intersects with the world line of observer 2 at point G, at $r=0$.
So far so good. But imagine, rather than just the first observer drawn, there were a series of freefalling light beacons that crossed the event horizon prior to observer 2 at a range of $T$ values, stretching into the past.
Once observer 2 has crossed the event horizon, is it correct that any light they receive from a beacon that has already crossed the horizon would appear to come from behind them? (Where behind means from the direction of increasing $r$).
Up until they reach the event horizon, the light received by observer 2 from all the beacons would come from the direction of decreasing $r$. So does that mean that as observer 2 crosses the event horizon they essentially "pass through" the images of all the beacons at once? And in fact, must they "pass through" the outward facing images of everything else that has previously fallen into the black hole? What on Earth would that look like?
Finally, what would be the Doppler shifts of the light received by observer 2 in these cases?