There is no per se rule that “double inclusion” is improper in a claim. In re Kelly, 305 F.2d 909, 916, 134 USPQ 397, 402 (CCPA 1962) (“Automatic reliance upon a ‘rule against double inclusion’ will lead to as many unreasonable interpretations as will automatic reliance upon a ‘rule allowing double inclusion’. The governing consideration is not double inclusion, but rather is what is a reasonable construction of the language of the claims.”). Older cases, such as Ex parte White, 127 USPQ 261 (Bd. App. 1958) and Ex parte Clark, 174 USPQ 40 (Bd. App. 1971) should be applied with care, according to the facts of each case.
The facts in each case must be evaluated to determine whether or not the multiple inclusion of one or more elements in a claim gives rise to indefiniteness in that claim. The mere fact that a compound may be embraced by more than one member of a Markush group recited in the claim does not lead to any uncertainty as to the scope of that claim for either examination or infringement purposes. On the other hand, where a claim directed to a device can be read to include the same element twice, the claim may be indefinite. Ex parte Kristensen, 10 USPQ2d 1701 (Bd. Pat. App. & Inter. 1989).