جَاءَنِي زَيْدٌ وَعَمْرٌو
Zayd and ʿAmr came to me.
«Wa» affirms that the predicate applies to both. By itself, it does not require that they arrived simultaneously or establish who came first. Temporal ordering requires additional contextual evidence.
This is why coordination is a precise rhetorical choice. The speaker can enumerate those involved while deliberately leaving timing unspecified; «wa» must not be equated with the successive sense of «fa» or «thumma».