Currently, it costs 500 Science - but the Steel Double Furnace costs 75 (matching the cost of Advanced Material Processing). Would be nice if this one did the same, costing 250 instead.

A config option to make both be unlocked with the prerequisite tech would also be nice (that way you could disable the double research if you wanted to).

Could also rename both researches since they're kinda verbose. I suggest "Double smelting" and "Advanced double smelting".

It looks like they changed the the cost of Advanced Material Processing at some point, as it used to be 500 in older versions.

If Raid is happy to bring it back in line I can do a PR for that.

The config option is a lot harder as it would require adding settings to the mod. That would need someone familiar with do that as I don't have the time to figure it out at the moment.

Renaming is easy but that choice is up to Raid. I can include the english rename in the PR if he is ok with it, but the other 2 languages i'd only be able to do with Google Translate.

PR is done for the cost change. I've been experimenting with adding settings to mods so if I have some free time and can get it working i'll look at the Config option to have it unlock with the pre-requisite tech

Version 0.6.4 contains both the cost update and the config option for research.