Fix doubled word typos

Author: NagyDonat

clang/lib/StaticAnalyzer/Core/ExprEngineCallAndReturn.cpp

@@ -678,13 +678,13 @@ void ExprEngine::evalCall(ExplodedNodeSet &Dst, ExplodedNode *Pred,
   // WARNING: As this function performs transitions between several different
   // states (perhaps in a branching structure) we must be careful to avoid
   // referencing obsolete or irrelevant states. In particular, 'CallEvent'
-  // instances have an attached state (because this is is convenient within the
+  // instances have an attached state (because this is convenient within the
   // checker callbacks) and it is our responsibility to keep these up-to-date.
   // In fact, the parameter 'CallTemplate' is a "template" because its attached
   // state may be older than the state of 'Pred' (which will be further
   // transformed by the transitions within this method).
   // (Note that 'runCheckersFor*Call' and 'finishArgumentConstruction' are
-  // prepared to take this template and and attach the proper state before
+  // prepared to take this template and attach the proper state before
   // forwarding it to the checkers.)
 
   // Run any pre-call checks using the generic call interface.