In this suggested sentence "aha.m tva.m pacchaa passaami", I suspect that it
would be more natural to exclude the "aha.m" subject unless one is wishing
to specially emphasize that it is *I* and not somebody else who sees you.
The subject "I" is included in the verb and so does not need to be expressed
additionally when unemphasized. This is a common error with people whose
languages are like English, not clearly marking the verbal subject via
suffixes. I imagine that this would be more obvious to an Italian speaker,
for example. Similarly, languages like Japanese are even more economical: a
Western learner might constuct the very stilted-sounding "watashi wa (I
subj) anata wo (you obj) mite imasu", while in many situations, in the
presence of the second person, one might just say "mite imasu".