  The Spectral Galaxy Pairs (SGPs) are defined as the composite galaxy spectra
which contain two independent redshift systems. These spectra are useful for
studying dust properties of the foreground galaxies. In this paper, a total of
165 spectra of SGPs are mined out from Sloan Digital Sky Survey (SDSS) Data
Release 9 (DR9) using the concept of membership degree from the fuzzy set
theory particularly defined to be suitable for fuzzily identifying emission
lines. The spectra and images of this sample are classified according to the
membership degree and their image features, respectively. Many of these 2nd
redshift systems are too small or too dim to select from the SDSS images alone,
making the sample a potentially unique source of information on dust effects in
low-luminosity or low-surface-brightness galaxies that are underrepresented in
morphological pair samples. The dust extinction of the objects with high
membership degree is also estimated by Balmer decrement. Additionally, analyses
for a series of spectroscopic observations of one SGP from 165 systems indicate
that a newly star-forming region of our Milky Way might occur.
