We report measurements of branching fractions and time-dependent CP asymmetries in B-0 -> D+D- and B-0 -> DD-+/-(-/+) decays using a data sample that contains (772 +/- 11) x 10(6)B (B) over bar pairs collected at the Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. We determine the branching fractions to be B(B-0 -> D+D-) = (2.12 +/- 0.16 +/- 0.18) X 10(-4) and B(B-0 -> DD-+/-(-/+)) = (6.14 +/- 0.29 +/- 0.50) x 10(-4). We measure CP asymmetry parameters SD+D- = -1.06(-0.14)(+0.21) +/- 0.08 and CD+D- = -0.43 +/- 0.16 +/- 0.05 in B-0 -> D+D- and A(DD) = +0.06 +/- 0.05 +/- 0.02, S-DD = -0.78 +/- 0.15 +/- 0.05, C-DD = -0.01 +/- 0.11 +/- 0.04, +/- Delta S-DD = -0.13 +/- 0.15 +/- 0.04 and Delta C-DD = +0.12 +/- 0.11 +/- 0.03 in B-0 -> DD-+/-(-/+), where the first uncertainty is statistical and the second is systematic. We exclude the conservation of CP symmetry in both decays at equal to or greater than 4 sigma significance.