In the latest FAQ they said that you can't when there are two armies with a strategem of the same name.
Before the FAQ I would agree with you.
Here is the quote from P4 of the FAQ for main rule book
Q: For the purposes of the Strategic Discipline matched play rule, are Stratagems with identical names that appear in different codexes (e.g. ‘Veterans of the Long War’, which is a Stratagem in Codex: Chaos Space Marines, Codex: Death Guard and Codex: Thousand Sons) considered to be the same Stratagem? A: Yes.