Questions about typing or writing errors come up on the forum from time to time (see example provided in comments). Posters are usually interested in:
- Term for describing the error.
- Frequency of occurrence.
- Cause and treatment.
Typos are common, and may improve with practice or training, though some conditions associated with more typos (eg, dyslexia, dyspraxia, dysgraphia) may prompt treatment. However, I am not aware of specific typographical errors being linked with specific conditions, except perhaps for spelling errors. As such, there is no value in classifying a particular error type for diagnostic purposes - it won't tell you anything useful about your brain.
There are several different ways to categorize typographical errors, depending on why you want to do so. For example, psycholinguists may find error classifications informative regarding the way our brain processes language; and historians may use error classifications to establish phylogeny of manuscripts. The term for a given error would consequently depend on the classification system used.
Human-computer interaction experts are also interested in error classification systems to help identify and prevent or correct common typing errors automatically. For example, Kano et al (2007) developed a classification system to help track children's progress with their typing skills. The researchers describe a number of previously developed classification systems, as well as the new system they developed, along with the frequency of occurrence of each type of error in studies conducted, so check out the paper for some rough estimates.
As an example, the type of error described in the question may be classified as an omission, fusion, blend, combination of word omission and insertion, space error, contamination, or substitution. In all cases, it appears to be rare relative to other kinds of typing errors.