(a) In a civil action against:
(1) a person who, from any cause, is legally incapable of testifying, or
(2) the committee, trustee, executor, administrator, heir, legatee, devisee, assignee, or other representative of a deceased person or of a person so incapable of testifying, a judgment or decree may not be rendered in favor of the plaintiff founded on the uncorroborated testimony of the plaintiff or of the agent, servant, or employee of the plaintiff as to any transaction with, or action, declaration or admission of, the deceased or incapable person.
(b) In an action specified by subsection (a) of this section, if the plaintiff or his agent, servant, or employee, testifies as to any transaction with, or action, declaration, or admission of, the deceased or incapable person, an entry, memorandum, or declaration, oral or written, by the deceased or incapable person, made while he was capable and upon his personal knowledge, may not be excluded as hearsay.