To successfully apply for a double degree, there are several factors to consider – and several LUT sections or external organisations you can reach out for help. The following list will help you to direct your question directly party that is able to best assist you:

Degree programme structure, courses, required prequisites, language proficiency requirements: 
your LUT study counsellor and head of the degree programme.

Tuition fees, tuition fee wavers and discounts during the double degree studies:
see here for more information and contact details.

International mobility grant for the double degree study period outside Finland (aka the exchange study grant): 
read more here or contact LUT International Mobility Services.

Technical issues on the LUT Mobility-Online application system and filling in the application form: 
LUT International Mobility Services

Relocating to another country as part of your double degree studies: 
visa, residence permits and work permits (for you and your family): this is handled exclusively by the immigration office in the receiving country – also the receiving non-Finnish university usually offers some guidance. However, LUT is unfortunately unable to comment or advice in these issues.