  Many low-luminosity active galactic nuclei (AGNs) contain a compact radio
core which can be observed with high angular resolution using very long
baseline interferometry (VLBI). Combining arcsec-scale structural information
with milliarcsec-resolution VLBI imaging is a useful way to characterise the
objects and to find compact cores on parsec scales. VLBI imaging could also be
employed to look for dual AGNs when the sources show kpc-scale double symmetric
structure with flat or inverted radio spectra. We observed five such sources at
redshifts 0.36 < z < 0.58 taken from an optically selected sample of Type 2
quasars with the European VLBI Network (EVN) at 1.7 and 5 GHz. Out of the five
sources, only one (SDSS J1026-0042) shows a confidently detected compact VLBI
core at both frequencies. The other four sources are marginally detected at 1.7
GHz only, indicating resolved-out radio structure and steep spectra. Using
first-epoch data from the ongoing Karl G. Jansky Very Large Array Sky Survey,
we confirm that indeed all four of these sources have steep radio spectra on
arcsec scale, contrary to the inverted spectra reported earlier in the
literature. However, the VLBI-detected source, SDSS J1026-0042, has a flat
integrated spectrum. Radio AGNs that show kpc-scale symmetric structures with
truly flat or inverted spectra could still be promising candidates of dual
AGNs, to be targeted with VLBI observations in the future.
