You mean your R2 is currently 6.8+8.2 ohms in series instead of a single 15 ohms? It will be fine to replace them with a single resistor if you are able to increase the power rating. The original split was probably done to divide the load between the two resistors, hence a lower wattage could do.
You should try and find non-inductive resistors, though. The larger power rating resistors are often made by winding resistive wire over the core, and they will have some inductance as well, which will affect the operation in audio frequency applications like this.
One solution to increase the power handling would be to use four 15 ohm resistors instead of one (two in series, and two of these combinations in parallel). That would divide by four the actual power a single resistor has to be able to dissipate, and probably even 1W resistors would do.
Anyway, the original damage must have required a prolonged play at near the maximum power these speakers can handle. If you don't feel like doing that daily, I would expect the original specs to be more than enough