You have chosen to use one of AutoCorrect's triggers to substitute a word and it is picking the first in your list. You want them unique up until a trigger (which is often punctuation).

1. Do not start the phrases with the same letter sequences.
2. I start some of mine with the underscore so that it won't pick up my ordinary typing.

Andrew's suggestions are good ones, as well.

References that may help you with AutoCorrect:

• Exploiting AutoCorrect by Suzanne Barnhill, MVP
• AutoCorrect