Pairs has the same bond order but different magnetic behaviour (one paramagnetic, one diamagnetic)?

Use molecular orbital configurations. $\mathrm{N_2}$ and $\mathrm{CO}$: both bond order $3$, both diamagnetic. $\mathrm{O_2^+}$ and $\mathrm{N_2^-}$ both have bond order $2.5$ and one unpaired electron each (both paramagnetic). $\mathrm{NO}$ has bond order $2.5$ while $\mathrm{O_2^-}$ has $1.5$. $\mathrm{O_2}$ has bond order $2$ with two unpaired electrons in $\pi^*2p$ (paramagnetic), while $\mathrm{C_2}$ has bond order $2$ with both $\pi2p$ orbitals filled and no unpaired electrons (diamagnetic). So $\mathrm{O_2}$ and $\mathrm{C_2}$ is the only pair with equal bond order but different magnetism.