My main bass is usually medium to high quality, so an American Fender Jazz/Precision, standard or Vintage Reissue, Music Man Stingray, German Warwick Streamer etc. Then my backup's or others tend to be something that's playable but cheaper, so a nice Mexican or Japanese Fender etc. They are not necessarily poorer in there ability, just financially less but still good enough to be played if I fancy playing something now and again rather than my main bass.
My current line up is a Music Man Stingray SR4 Fretless as my main bass and then I have a Mexican Fender Precision 70's Reissue and an Japanese ESP 400 Series Jazz. The Stingray is worth about £2k and he backup's are worth about £700 each. All perfect and all very playable. However, I have been thinking about getting a much cheaper backup bass, something like a Squire Vintage Modified Fretless Jazz as most of the time I play my Stingray and the backup just sits on the side looking pretty. Seems silly dragging a half decent bass out to sit on the side rarely to be played.