Herein we report the structure, magnetic and dielectric properties of Y2CoMnO6 (YCMO) and Y2NiMnO6 (YNMO) prepared under various conditions. On annealing in inert atmosphere, YCMO sample shows a partial decomposition while YNMO remains unaffected. Both YCMO and YNMO samples show paramagnetic to ferromagnetic transition around 80 K, but only the magnetic properties of YCMO samples depend on the preparation conditions. YCMO samples show antiferromagnetic ground state in zero field and a metamagnetic transition at relatively low field (similar to 2 T). Differences in the annealing environment do not destroy the initial antiparallel spin order in YCMO, but affect the critical fields of metamagnetic transition. The field-dependent magnetic properties indicated soft ferromagnetic nature of YNMO samples. The dielectric measurements show distinct frequency and temperature-dependent features in YCMO samples compared to YNMO samples. A large relative permittivity with epsilon? of about 10(4) is observed in both O-2 and air-annealed YCMO samples. Multiple dielectric relaxations are observed in all the annealed YCMO and YNMO samples.