Conditionally, yes. But also no. It really depends, and there's no simple conversion from one d100 system to another.

Here's a few pointers on what to check if you want to re-make a character in another system than the character was in originally.

Attributes. Is it the same number of attributes, or at least reasonably clear what goes where? Are the normal ranges for the attributes the same in both systems, or at least easily converted?

Magic. This is a big one. Call of Cthulhu, for instance, tends to handle magic as a soul-destroying power that will leave you gibbering and possibly growing tentacles. Or at least thinking that you're growing tentacles. Or both. Whichever. In other settings, magic is more of a known factor, and doesn't necessarily have any intrinsic cost to your sanity. Which leads us to ...

System or setting specific things. In Call of Cthulhu, for instance, Sanity is a core concept. If the concept doesn't reasonably match a concept in the system you're converting to, you'll have a difficult time capturing that aspect in the originating system.

And then there's how equipment is implemented and all that, but usually you can work around that.

So, basically, even though the system uses the same die, it doesn't mean that there's a conversion that is easily done without re-making the character. Consider, say, RMSS, MERP, RM2, or SpaceMaster 2nd edition. All of which tend to use a d100-roll, add a bonus, subtract a negative, cross-index with a table, get a result.

Even within that closely related family of games, you'll have difficulty converting without potentially re-making the character (because of differences in skill lists and so on).

Then, add another (old) d100-system, such as Buck Rogers in the XXV Century. There, you're using a system where you have a skill rating, plus your relevant attribute, take the result and multiply by a roll difficulty, and that's what you need to roll equal to or lower. (Example: Pilot Rocket 55 + Dex 15 = 70, multiply by difficulty Easy x2, 140 - roll anything lower than 100 and you're golden)

Even though the roll is superficially the same - a d100 - the system can and will trip you up. And you'll have much the same issue with going from RuneQuest 6e (which is essentially Mythras) to Call of Cthulhu 7e, even though the two are perhaps much more closely related than the examples I gave, above.

There's both a craft and an art to converting characters while staying true to a 'core' of any given character, and it tends to translate into some fudging and intuition rather than a strictly mathematical process.