Above left and right: The first time Danny sees the twins, he's in the hotel recreation room playing darts.
Later in the movie, after having just made a right turn while riding his tricycle at the entrance to one of the Overlook's many corridors (top left), Danny next comes to a wall which forces him to turn left (top right). Immediately after turning left, Danny encounters the twins and stops moving (above left). The fact that the girls are wearing blue dresses means that they symbolize an 'evil feminine' presence. Danny's vision of the twins standing, alternates with one of seeing both of them dead (above right).
The above set of screencaps shows how each time the camera cuts to the standing twins, between shots of of Danny's face, and the dead twins, the (standing) twins appear to get closer to Danny.
The final time we're shown the dead twins (above left), Danny has an extrememly horrified expression on his face (above right).
Referring to the sets of screencaps above, the first time Danny sees the twins, his attention had previously been diverted - he was playing darts. It is implied that he had been wrapped up in his own amusement, and kept playing for a while with them standing there, not noticing them. Regarding the screencaps showing Danny riding his tricycle, then coming to a stop when he sees the twins, recall from earlier in the analysis that Carl Jung says, "[A] leftward movement is equivalent to a movement in the direction of the unconscious, whereas a movement to the right...aims at consciousness."[a] A clockwise motion is a movement toward the right, and thus, toward the conscious, which is, according to Jung, a movement toward the "correct" side; and a counterclockwise motion is one to the left, and thus the unconscious, which Jung calls the "sinister" side. By turning left while riding in the hallway, Danny has made a movement toward evil and is now confronted by a great danger: the twins, representing the imbalanced duality of his own mother (representing that of Susan Robertson), as well as a more general 'duality of Woman'. The fact that the (standing) twins appear to get closer to Danny, as he views them, indicates that Danny will directly confront this danger that they represent.
In a later scene in the movie, in which Danny is again riding his tricycle (shown at left), it can be seen that he is wearing red, white, and blue clothing (the white is in his sneakers); the national flag of the United States of America (shown above) consists of these same three colors, so Danny represents some component of the American public. As stated earlier in the analysis, Danny looks like he's 6 years old; then, since the movie is set in 1977, Danny specifically represents those Americans, or at least those American males, born into the generation which includes the birth year 1971; i.e., what is now called Generation X (those people born during approximately the years 1965 - 1983). Therefore, within a societal context, what Kubrick is saying (or more correctly, predicting), is that the men of Generation X will occupy themselves with their own amusing diversions to the extent that they will be tardy in seeing the threatening presence of the 'duality of Woman', which will have actually already been around for a while. Note that in this view of Danny from behind, the blue upper straps of his overalls, in combination with the shape and color of the tricycle seat-back, makes Danny appear to be wearing a blue dress. This indicates that Susan's duality has had a feminizing effect on her son.
Going back to the point in the movie at which Danny last sees the dead and bloodied twins, Danny covers his eyes (top left) upon his final seeing of them (immediately after having the extremely horrified expression on his face shown earlier above); then a few moments later, when he looks again (top right), the girls are gone (above left). Next, 'Tony' tries to convince Danny that the twins weren't real (above right).
The fact that Danny (via Tony) tries to convince himself that the twins were just in his imagination, indicates that Kubrick was predicting that the men of Generation X (and the American public in general), will (wrongly) try to convince themselves that the aforementioned 'duality of Woman' is not real, or that it is nothing to worry about.
a. Jung, C.G. The Collected Works of C.G. Jung, Vol. 12. Princeton University Press, 1968. p. 127.
