Short answer. Yes. When two or more borrowers sign the same commodatum contract, the Civil Code makes them solidarily liable. The lender can demand the entire value from either of you. Paying it yourself does not end the matter — you then have the right to seek reimbursement from the other borrower.
What the law says
When there are two or more bailees to whom a thing is loaned in the same contract, they are liable solidarily.
Civil Code, Article 1945 — Solidary Liability of Bailees. Read the full provision →
Solidary liability in a commodatum
Article 1945 of the Civil Code is blunt: When there are two or more bailees to whom a thing is loaned in the same contract, they are liable solidarily. A commodatum is a loan where the thing itself must be returned — not money, but the actual item (a vehicle, a machine, a piece of equipment). When two people borrow that thing together under one agreement and it is lost or damaged, the lender does not have to chase both of them proportionally. Either one can be compelled to answer for the full liability.
What solidary liability means for you
In a solidary obligation, each debtor is liable for the entire obligation. The lender chooses whom to sue and for how much — up to the full value. If you are the one who is easier to find, has assets, or is simply presented with a demand first, you bear the full pressure. You cannot tell the lender to go after the other borrower for half. The other borrower is equally liable, but the lender's right to collect in full from either of you is what makes this solidary rather than joint.
Your right to recover from the other borrower
Paying in full does not mean you absorb the entire loss. If you pay the lender the full value of the lost thing, you acquire the right to demand reimbursement from the other borrower for his proportionate share. This right — called the right of contribution — exists between co-debtors in solidary obligations. In a two-person borrowing, that typically means recovering half from the other. If the loss was due to the other borrower's fault, your claim against him may be even stronger. But none of this affects the lender, who has already been made whole.
Why the law imposes solidary liability here
The reason for this rule is practical: a commodatum lends a specific, often irreplaceable thing. If both borrowers were only proportionally liable, the lender would be forced to pursue two separate claims for partial amounts — a significant burden when all he wants is to be compensated for the loss of his property. Solidary liability protects the lender by making recovery efficient. It places the burden of sorting out internal responsibility on the borrowers themselves, who are better positioned to know what happened and who was at fault.