LG Better Meta 1.8.0 and MSM: "Undefined index" error

I’m working on brand new site running EE 1.6.8 and a fresh install of LG Better Meta 1.8.0. Things were going just fine, but I’ve begun work on the second site (I’m using the MSM) and have run into an odd error.

I’ve set up meta info for several of the second site’s pages, without an issue. However, on one of the pages, I get this error:

Notice: Undefined index: 1 in /.../plugins/pi.lg_better_meta_pl.php on line 278

Notice: Undefined index: 1 in /.../plugins/pi.lg_better_meta_pl.php on line 283

Notice: Undefined index: 1 in /.../plugins/pi.lg_better_meta_pl.php on line 288

I did some searching on the forums, and found a mention of it here, but I performed the recommended fixes (e.g., saving out the extension settings for the second site, verifying that the right columns are in the “exp_lg_better_meta” table). But nothing works.

I did, however, notice that the page that displays the error shares the same URL title as a page on the first MSM site. When I change it to something else, the error disappears. And I was able to replicate it on some other pages on the second MSM site.

So it looks like there’s some conflict there. But I don’t know how to go about resolving it short of making sure that all of the my pages have different URL titles – which will be increasingly difficult as I add more sites to the MSM.