No, it’s not a problem. The CL reader always reads symbols as a function of the current package. The current package has import lists of other packages, and the symbol resolution is well defined.
In the case that you want to import symbols from other packages and deal with conflicts, there are ways of doing this, and if you want to import symbols from another package but not some from that package, that’s possible as well.
However, give a package in a current state, the read function reads into that package. If there are conflicts, conditions are raised, and there may be condition handlers in place to handle them. For example if read encounters text such as aaa:bbb or aaa::ccc and package aaa does not exist, or does not export the symbols bbb or does not contain the symbol ccc, then conditions are raised.