Both Dragon® Premium and Pro?
Unfortunately, it is not possible to install both of these versions on the same Windows computer. Installing Dragon Naturally Speaking Professional v11 English would facilitate an upgrade of Dragon Premium, and Dragon Premium would not install over Dragon Professional.
How to Get Both Languages
We recommend installing the Spanish edition of Dragon Naturally Speaking Professional, which includes both Spanish and English language support. This would allow you to have all the features of the Professional version, along with both English and Spanish languages.
Verification Source
Nuance Technical Support