No. An offer is not an immigration decision, and the actual application structure needs to be identified and assessed.
Distinguish the proposals from the cases
Each proposed principal remains subject to the appropriate eligibility, admissibility and visa-availability requirements. Do not present two letters of intent as approval of two applications or as automatic authority to switch between principal and spouse roles. Choosing which spouse becomes the principal applicant is a strategic decision, not a formality, and it should be made once rather than revisited case by case as offers arrive.
Compare the strength of each underlying classification, the completeness of each supporting record, and how far along each employer's own process already is before settling on a single structure. Running independent petitions in parallel, each naming a different spouse as principal, invites inconsistent or duplicate filings and can create confusion about which household members are being claimed as dependents on which case. Once a structure is chosen, keep the secondary offer as a documented contingency rather than an active parallel filing, and update counsel immediately if either employer's circumstances change.
Switching the principal role mid-process is sometimes possible, but it generally means restarting significant parts of the evidentiary record rather than simply relabeling the existing one. Treat the decision as a shared household strategy, with a single timeline, rather than separate employer relationships proceeding independently of each other.