Schematic illustration of the lensing situations that allow the light from two stars in separate star clusters to blend together in the image plane forming a two-component SED. (a) The situation in the source plane, with three stars (1, 2 and 3) located close to each other and within ∼1 pc of the caustic curve. A fourth star (4) is located at a similar distance from the caustic as 1, but up to ≈100 pc away in the direction along the caustic. (b) The corresponding image-plane situation, where the stars 2 and 3 appear as resolved double images (2ab, 3ab) with a separation that increases with their distance from the caustic in (a). The images of stars 1 and 4, on the other hand, form two sets of overlapping image pairs (1ab and 4ab) at very high magnification, separated by only a small distance from the critical curve. Since the radial magnification μ_r is much smaller than the tangential magnification μ_t along the critical curve (by a factor of μ_r/μ_t ≲ 0.01), the two image pairs 1ab and 4ab may appear as an unresolved source at the angular resolution of JWST.