There's no problem with the physics of adding two current sources together to charge a single battery. The problem might come with the control.
Battery chargers tend to be programmed to
a) charge the battery as quickly as possible
b) not overcharge the battery
It's easy for two parallel chargers to each limit the voltage to the battery. They will have slightly different thresholds, but that really doesn't matter.
The problem comes with current. Perhaps the safest way to parallel two chargers is to allocate each charger 50% of your battery's maximum charge current (or 30/70, or some other fixed fraction). Unfortnuately with a strong wind at night, or a calm sunny day, the maximum charge rate will be limited by your chargers at below the maximum possible for the battery.
Ideally you'd like either charger to charge up to the maximum rate of your battery, but limit the total current on a windy sunny day. That means they have to know about each other, and play nice. The feature needs to have been anticipated and included by the controllers' designers.
If they are only standalone chargers, but both have a digital port, and can report current and be controlled on the fly, then you can tack on an Arduino or PI, and control the limits yourself.
If they don't have digital control, you may be able to do something on the analogue side, but you'd need to know what you were doing.