The Greek stars of Argo Navis

Carina	Puppis	Vela
α	ζ	γ¹
β	ν	γ²
ε	ξ	δ
η	o *	κ
ϑ	π	λ
ι	ρ	μ
υ^A	σ	o *
υ^B	τ	φ
χ		ψ
ω

* The fact that there are two omicrons leads one to suspect that somewhere along the way a cataloguer misread an English "o" for a Greek omicron.

Both Vela and Puppis have many 'Latin' or English letters, upper case and lower case. If one studies Tirion's SkyAtlas 2000.0, one discovers that Vela has both a Greek omicron and an English "o", while Puppis has no English "o" but does have a Greek omicron.

The Greek stars of Argo Navis

Therefore I suspect that omicron Puppis was originally an English "o" and was misread some time ago into a Greek omicron, and the label has stuck.