If direct and indirect/non-direct objects differ in their morphological coding (at least minimally), then they will also differ in their syntactic behaviour (at least minimally), (but not necessarily the reverse).
Standardized
IF direct and indirect/non-direct objects differ in their morphological coding (at least minimally), THEN they will also differ in their syntactic behavior (at least minimally), but not necessarily vice versa.
Keywords
grammatical relations, object, indirect, non-direct, direct
##953,955, and 956 seem to me identical. Why list them three times!?