How do I know if I can double, triple or quadruple a recipe for caramels?
The short answer is yes, but I would do it by weight and absolutely not by volume.

A lot depends on how many times you are scaling up your recipe. With high viscosity materials, mixing small amounts is trivial, but with large enough amounts, the geometry of your mixing vessel and the type of hook/blade/impeller all matter, and matter to the point the sometimes the recipe itself needed changing. It is all about mass transfer. The same with heat transfer during cooking, hot spots and uneven temperature distribution are common problems. Without knowing the specifics, it would not be possible to calculate what "large enough" is. Twice is probably fine. Quadruple the batch, you might want to look out for mixing and heating issues.

A bit off-topic, when it comes to the economics of making a recipe into a business, allowances for wastage, measurement inaccuracies, ingredient and product losses do pile up when scaled up. These are unnoticeable in a small batch in a home kitchen. Hygiene when scaled up becomes disproportionately effect and cost intensive too. Budgeting errors lurk everywhere even for very experienced finance minded people. Underestimating power consumption is also common.