NaHCO3 and NaOH compounds cannot exist together in solution as
NaHCO3+NaOH→Neutral saltNa2CO3+H2O
If acid and base present in same solution then they would react and NaHCO3 is a slightly acidic compound, while NaOH is a base. H-atom of NaHCO3 replace by base, i.e. NaOH, give Na2CO3 and water