one says MP | 423
ib2tight is right.
This pill is
GUAIFENESIN CR 600 MG, by Mutual.
Imprint Code MP 423
Description green, oblong, scored tablet
Info at
http://guaifenesin.drugs.com The other has a symbol (a line with half a circle on either side) then 417.
This pill is GUAIFENESIN CR 600 MG, by Duramed.
Imprint Code dp 417
Description light green, oblong, scored tablet
Info at
http://guaifenesin.drugs.com