In the November 1973 Word Ways, Will Shortz quoted George Canning's famous eighteenth-century conundrum involving the words cares and caress. There are many other words exhibiting this property, as the following verse suggests.
Espy, Willard R.
"A Plurality of Singular Verse,"
Word Ways: Vol. 7
, Article 14.
Available at: http://digitalcommons.butler.edu/wordways/vol7/iss2/14